Why a PSMA PET Scan Comes Before Lutetium-177 PSMA Therapy and What It Has to Show

The appointment letter says two things: a scan next week, then a meeting to talk about “the lutetium.” A man who has already been through surgery, hormone treatment and chemotherapy reads it twice and asks the obvious question. If the doctors have already decided on the treatment, why another scan?

The honest answer is that nobody has decided yet. A PSMA PET scan before lutetium therapy is not a formality on the way to an infusion chair; it is the audition. The treatment is a radioactive molecule built to find one specific protein on prostate cancer cells. If the scan cannot see that protein on the tumors, the drug will not find it either.

This explainer walks through what the scan is actually looking for, what a “good” result looks like to a nuclear medicine physician, where the images can mislead, and what the weeks on either side usually feel like. The final call always sits with the treating team, but the reasoning behind it should not be a mystery.

What a PSMA PET scan before lutetium therapy is actually looking for

PSMA stands for prostate-specific membrane antigen, a protein that sits on the surface of most prostate cancer cells in far greater amounts than on healthy tissue. A PSMA PET scan uses a small amount of a radioactive tracer that sticks to that protein, then photographs where the tracer has gathered. Bright spots on the image are places where the protein, and very likely the cancer, is concentrated.

Two tracers are in common use. One is labeled with gallium-68, the other with fluorine-18. Both bind PSMA; they differ mainly in how they are produced and in how they leave the body, which affects how the bladder, bowel and liver appear on the pictures. Your report will name the tracer used.

The PET camera is paired with a CT scanner in the same machine, so every glowing spot is mapped onto anatomy. That pairing matters. A bright focus in a rib means something different from the same brightness in a ureter carrying urine, and the CT helps the reading physician tell them apart.

Before lutetium therapy the question the scan must answer is narrow and practical. It is not “is there cancer?” The team already knows there is. It is “does every meaningful deposit of this cancer carry enough PSMA for a PSMA-seeking drug to reach it?” Think of the scan as a rehearsal: the tracer travels the same route the treatment will take, binds the same target, and shows in advance where the therapy would land. If the rehearsal finds the stage empty, the performance is called off.

How lutetium-177 PSMA therapy works, in plain language

Lutetium-177 PSMA therapy belongs to a class of treatments called radioligand therapy, sometimes shortened to radiopharmaceutical therapy. A ligand is simply a molecule designed to bind a specific target; here the target is PSMA. Attached to that ligand is lutetium-177, a radioactive metal that gives off beta particles, a type of radiation that travels only a few millimeters through tissue.

The drug is given by injection into a vein. It circulates, docks onto PSMA wherever it finds it, and is pulled inside the cancer cell. There the lutetium releases its radiation, damaging the DNA of that cell and, because of the short range, of its close neighbors. Tissue further away receives very little. The practical result is internal radiation aimed at every PSMA-rich deposit at once, whether in bone, lymph nodes or organs.

That mechanism explains the whole logic of the pre-treatment scan. External beam radiotherapy is aimed by a machine at a location the team chooses. Lutetium-177 PSMA therapy is aimed by biology; the drug goes where the protein is and nowhere else. A tumor with little PSMA on its surface is, from the drug’s point of view, invisible.

Healthy tissues that carry some PSMA also take up a little of the drug, which is why salivary glands, kidneys and bone marrow are watched closely. The treatment is given as a course of infusions spaced weeks apart, with blood tests and clinical review between them. How many infusions, how far apart, and whether to pause or stop are decisions the prescribing team makes as the course unfolds, based on response and blood counts.

Why one scan decides so much: the see-and-treat idea

Nuclear medicine physicians use the word theranostics for pairs of drugs built from the same molecule, one carrying an imaging label and one carrying a treatment label. The PSMA tracer in the scanner and the PSMA drug in the infusion are near-identical keys for the same lock. Whatever the imaging key opens, the treatment key should open too.

This is unusual in cancer care. Most systemic treatments are chosen on the basis of cancer type, prior therapies and general fitness, then judged by whether the PSA level and scans improve months later. Radioligand therapy offers something closer to a preview. If the target is visible before treatment, the drug has somewhere to go. If it is not, months of treatment and side effects can be avoided before they start.

The pivotal randomized trial of lutetium-177 PSMA therapy, published in the New England Journal of Medicine and indexed on PubMed, was designed around this principle. Every participant had a PSMA PET scan first, and only men whose scans met defined criteria were enrolled. Roughly one in eight of the men screened were excluded on imaging grounds alone (PubMed 34161051). That figure is a reminder that the scan is a genuine filter, not a rubber stamp.

There is a second, quieter benefit. The pre-treatment scan becomes the baseline against which later scans are compared. A deposit that was bright and later fades tells one story; a new spot that appears where nothing glowed before tells another. Without the first picture, the team is judging response with one eye closed.

What the PSMA PET scan has to show before lutetium therapy

Reading physicians do not simply look for “lots of glow.” They apply criteria, and the most widely referenced ones come from the pivotal trial mentioned above (PubMed 34161051). Two conditions had to be met.

First, at least one tumor deposit had to take up more tracer than the normal liver does. The liver is used as an internal reference because it collects a moderate, predictable amount of tracer; any lesion brighter than the liver is judged to carry enough PSMA to be a worthwhile target.

Second, and often more decisive, there could be no PSMA-negative lesion above a certain size. The trial defined these thresholds on the CT part of the scan: lymph nodes with a short axis of 2.5 cm or more, organ deposits of 1 cm or more, and bone lesions with a soft-tissue component of 1 cm or more. A sizeable deposit that fails to light up is a warning sign that part of the cancer has stopped displaying PSMA and would escape the treatment.

Scan finding	What it usually means for eligibility
All known lesions brighter than liver	Favorable pattern; team proceeds to assess fitness and blood work
Most lesions bright, one large non-avid deposit	Often a reason to pause; further imaging or alternatives discussed
Lesions visible but fainter than liver	Low target expression; benefit uncertain, other options considered
Extensive disease on CT with little tracer uptake	Usually not suitable for PSMA-directed therapy

Individual centers and national guidance may adapt these thresholds, so ask how your team applies them.

Lutetium-177 PSMA therapy eligibility: who is usually offered it and who is asked to wait

The scan is necessary but not sufficient. Eligibility rests on a wider picture, and the trial population that generated most of the evidence describes it well. Participants had metastatic castration-resistant prostate cancer, meaning the disease had spread and kept growing despite hormone therapy that lowers testosterone. They had already received at least one newer hormonal agent, known as an androgen receptor pathway inhibitor, and at least one taxane chemotherapy (PubMed 34161051). Prostate cancer treatment pathways summarized by the National Cancer Institute describe these earlier steps in detail.

Fitness matters as much as scan results. Because the drug touches kidneys and bone marrow, teams look for adequate kidney function and reasonable blood counts before each infusion. Someone whose marrow is already exhausted by previous chemotherapy or by cancer crowding out normal cells may be asked to wait, or may be told the risk outweighs the likely benefit.

Who is typically asked to wait, rather than told no? A few common situations:

• Men whose current treatment is still working, where the scan is done for planning but the therapy is held in reserve.
• Men with a recent change in hormone therapy, since PSMA expression can shift for a while afterward and a repeat scan may be clearer.
• Men recovering from a recent infection, a fracture or a hospital stay, until blood counts and strength return.

Research continues into whether the treatment helps earlier in the disease, before chemotherapy, and some regions already permit that use. Whether it applies to you depends on local approval, guideline position and, above all, the judgment of your prescribing team.

How accurate is a PSMA PET scan for prostate cancer?

Accuracy is a fair question, because a scan that misses disease or invents it would make a poor gatekeeper. The strongest head-to-head evidence comes from a randomized Australian trial of men with high-risk prostate cancer before initial treatment, published in The Lancet (PubMed 32209449). PSMA PET/CT identified the true extent of disease with about 92 percent accuracy, compared with roughly 65 percent for the conventional combination of CT and bone scan. The PSMA scan also produced fewer uncertain findings and changed management more often.

Two cautions keep that number honest. That trial studied newly diagnosed men, not men with advanced disease heading toward radioligand therapy, so the figures do not transfer exactly. And “accuracy” measured against later pathology or follow-up imaging is not the same as “predicts response to treatment,” which is the question that matters most before lutetium therapy.

In the advanced setting, the scan’s job is less about finding hidden disease and more about characterizing known disease. Here its strength is sensitivity: PSMA PET routinely shows deposits a few millimeters across that CT alone would call normal, particularly in lymph nodes and bone. Its weakness is that brightness tracks the protein, not aggressiveness. A dim lesion may be dim because it is small, because it carries little PSMA, or because it is not cancer at all.

For the reader, the useful takeaway is this: a PSMA PET scan is among the most accurate imaging tests available for prostate cancer, and it is still an image, interpreted by a human, of a protein rather than of the cancer itself. Your team reads it alongside PSA trends, previous scans and, occasionally, a biopsy.

What are the potential pitfalls of a PSMA PET scan?

Every imaging test has ways of misleading, and PSMA PET is no exception. Knowing the common traps helps you understand why a report may carry hedged language such as “indeterminate” or “favored benign.”

Normal tissues take up the tracer. Salivary glands, lacrimal glands, kidneys, liver, spleen and parts of the bowel all glow to some degree, and small nerve bundles called ganglia near the spine can look remarkably like lymph nodes. Experienced readers recognize these patterns, but they are a frequent source of second looks.

Urine is radioactive during the scan. Tracer excreted through the kidneys travels down the ureters and pools in the bladder. A dot of activity in a ureter can imitate a pelvic lymph node, and bladder activity can obscure the prostate bed itself. Some tracers and some protocols reduce this problem; none abolish it.

Not everything bright is prostate cancer. Healing fractures, benign bone conditions such as fibrous dysplasia or Paget disease, some other cancers, and even certain benign tumors express PSMA or mimic its signal. A solitary bright rib in a man with no other disease usually earns a closer CT look rather than an instant label.

Not everything dark is clear. Deposits below the scanner’s resolution, typically a few millimeters, can hide. More importantly for this decision, some advanced cancers shed PSMA as they evolve, particularly those that take on neuroendocrine features. Those tumors can be large on CT and nearly invisible on PET, which is exactly the mismatch the eligibility criteria are designed to catch. Recent changes in hormone therapy can also shift PSMA expression for a time, which is why the timing of the scan is discussed rather than assumed.

Is it okay to eat before a PSMA PET scan? Preparation and the day itself

For most PSMA tracers, yes, and this surprises people who have had a different kind of PET scan before. The widely used glucose-based tracer (FDG) requires fasting because food raises blood sugar and competes with the tracer. PSMA tracers do not depend on sugar metabolism, so many centers allow a normal light meal. That said, protocols vary, and some departments still ask for a few hours without food or restrict certain medicines. The instruction sheet from your own center overrides anything written here.

Hydration is encouraged almost everywhere. Drinking water before and after helps flush tracer through the kidneys and bladder, which improves image quality around the pelvis and shortens the time radioactivity lingers in the body. Guidance on general PET preparation from the NHS and Mayo Clinic covers what to wear, when to remove metal, and when to mention pregnancy in a companion, since the person scanned will be mildly radioactive for a few hours.

On the day, expect roughly this sequence. A cannula is placed in a vein and the tracer injected, which most people barely feel. There is then a waiting period, commonly around an hour, while the tracer distributes; you will be asked to sit quietly and to empty your bladder just before imaging. The scan itself takes about 20 to 45 minutes lying still on a narrow table that moves through a ring-shaped scanner. The NHS PET scan guidance describes this general timing, and PSMA protocols follow a similar shape.

Bring a list of your medicines, the date your last hormone injection or tablet regimen changed, and any prior scan reports from elsewhere. Those details help the reading physician interpret the pictures correctly.

What happens if the scan shows PSMA-negative or mixed disease

A disappointing scan is not a dead end; it is information that redirects the conversation. The result usually falls into one of three patterns, and each leads somewhere different.

The first is genuinely low uptake everywhere. The cancer is visible on CT, blood tests confirm it is active, yet the PSMA signal is faint. This suggests the cells are not displaying the target, and PSMA-directed therapy is unlikely to reach them. Teams then return to the wider menu: further chemotherapy, a different hormonal agent, treatments matched to specific genetic changes in the tumor, bone-targeted agents, radiotherapy to painful sites, and clinical trials. The National Cancer Institute’s prostate cancer treatment summary outlines these categories.

The second pattern is discordance: most deposits are bright, but one or more sizeable lesions are dark. Some centers add a second scan using the glucose-based FDG tracer to characterize the dark spots. A lesion that is FDG-avid but PSMA-negative is metabolically active cancer that has changed its behavior, and it would be untouched by lutetium. Depending on how much of the disease behaves this way, the team may propose treating the discordant site separately, choosing a different systemic therapy, or occasionally sampling it with a biopsy.

The third pattern is uncertainty about timing. If hormone therapy changed recently, or if the scan quality was compromised, a repeat scan after a few weeks may give a clearer answer.

Whatever the pattern, ask your team to explain which category your scan fell into and why. The images belong to you, and a clear explanation of a negative result is as much a part of good care as a positive one.

What is the success rate of lutetium-177 PSMA therapy? What the evidence shows

There is no single success rate, and any figure offered as one deserves suspicion. What exists is trial evidence in defined groups of men, and the most cited comes from the randomized phase 3 study of 831 participants with PSMA-positive metastatic castration-resistant disease who had already received hormonal agents and chemotherapy (PubMed 34161051).

In that trial, men who received lutetium-177 PSMA therapy alongside standard care lived a median of 15.3 months, compared with 11.3 months for standard care alone. The time before the cancer visibly progressed on imaging was also longer, a median of 8.7 months versus 3.4 months. Around 46 percent of treated men saw their PSA fall by at least half. Those are meaningful differences, and they are also modest ones: this was a treatment for late-stage disease, and it extended life for the group rather than halting the illness.

Several points keep those numbers in proportion. Medians describe the middle of a range; some men did far better and some far worse, and the scan cannot yet tell an individual which he will be. The participants were selected by PSMA PET, so the results describe men whose scans already met the criteria and say nothing about those who did not. And the comparison arm received standard care of the time, which continues to evolve.

Ongoing trials are testing the treatment earlier in the disease, in combination with other drugs, and with different imaging thresholds. Until those report, the honest summary is that lutetium-177 PSMA therapy has shown a survival benefit in a carefully selected population, that the PSMA PET scan is how that population is identified, and that the outcome for any one person remains a matter of probability rather than promise.

What the following days and weeks usually look like

After the scan, the practical steps are simple. The tracer decays within hours, and most centers ask you to keep drinking fluids and to keep some distance from small children and pregnant women for the rest of the day, in line with general PET guidance from the NHS. There are no lasting effects from the scan itself, and normal activities resume the same evening.

The report usually reaches your team within days, though the decisive conversation often waits for a multidisciplinary meeting where nuclear medicine physicians, oncologists, urologists and radiologists review the images together. Blood tests for kidney function and blood counts are typically drawn in the same window. The interval between scan and first infusion is usually measured in weeks rather than months, partly because the scan should reflect the disease as it is now; a picture from many months earlier may no longer be trusted.

The first treatment day is longer than the scan. The infusion itself is brief, but there is preparation, monitoring afterward and radiation-safety counseling before you leave. Because the drug is excreted in urine for several days, you will be given specific instructions about bathroom hygiene, laundry, sleeping arrangements and contact with others. These are precautionary and time-limited; your center will tell you exactly how long they apply.

In the weeks between infusions, fatigue is the most common companion, and a dry mouth can appear within days. Blood tests are repeated before each session to check that the marrow and kidneys have recovered enough to continue. Response is judged by PSA trends and, at intervals, by repeat imaging compared against the pre-treatment scan. Your team decides at each step whether to continue, pause or stop.

Side effects the pre-treatment scan helps anticipate

The normal-tissue uptake that complicates scan reading has a useful flip side: it shows in advance which healthy organs will receive some radiation. The same trial that established the survival benefit also catalogued side effects in detail (PubMed 34161051), and they map neatly onto the glowing organs of a typical PSMA scan.

Salivary glands take up the drug, and dry mouth was reported by about 39 percent of treated men in that trial. For most it was mild and manageable with sips of water, sugar-free lozenges and attention to dental care, but it can affect taste and comfort with eating. Ice packs and other protective measures have been studied with mixed results, and your team will describe what it offers.

Bone marrow is exposed because much of the disease, and therefore much of the radiation, sits in bone. Low red cell counts (anemia) occurred in roughly 32 percent of treated men and low platelets in about 17 percent. These are the reason for the blood tests before every infusion and for the red-flag symptoms described later in this article. Men whose scans show very extensive bone disease are warned that marrow effects may be more pronounced.

Kidneys clear the drug and receive some radiation on the way; kidney function is tracked throughout, and pre-existing kidney disease is weighed carefully before starting. Fatigue affected around 43 percent and nausea about 35 percent, usually in the days after each infusion.

None of these effects is guaranteed, and none is a reason on its own to decline treatment. They are reasons to plan: to sort out dental checks beforehand, to arrange help for the tired days, and to know whom to call.

What people often get wrong about PSMA scans and lutetium therapy

“If the scan lights up brightly, the treatment will definitely work.” A bright scan means the target is present and the drug can reach it. It does not guarantee the cancer will respond, and it cannot predict how long any benefit lasts. Eligibility and effectiveness are related but separate ideas.

“A negative scan means the cancer is gone.” In a man with a rising PSA and visible disease on CT, a faint PSMA scan more often means the cancer has stopped displaying the protein than that it has disappeared. It is a change in the cancer’s character, and usually an unwelcome one, not an all-clear.

“Any old PSMA scan will do.” Prostate cancer evolves, and PSMA expression can shift with treatment. Teams generally want a scan that reflects the disease as it stands close to the planned start of therapy, not a picture from a year ago.

“Lutetium therapy is a last resort with nothing to lose.” It carries real side effects, particularly for the bone marrow, and a man who is frail or whose marrow is already struggling may be harmed more than helped. The scan, blood tests and fitness assessment exist because the decision is a genuine weighing of risks.

“The scan itself is dangerous.” The tracer dose is small, decays within hours, and is comparable to other nuclear medicine tests described by MedlinePlus and the NHS. The precautions around children and pregnant contacts are brief and cautious rather than a sign of hazard.

“Success rates are around X percent.” Numbers quoted without a trial name, a population and an outcome measure are marketing, not medicine. Ask what was measured, in whom, and compared with what.

Questions to ask your care team

Bringing written questions to the results appointment changes its shape. The team knows the images; you know what you need to hear. These prompts are a starting point, not a script.

• Which tracer was used for my scan, and were the pictures of good technical quality?
• Did every known site of my cancer take up the tracer more strongly than my liver, and were there any deposits that did not light up?
• Were any findings uncertain, and if so, how did you decide what they were?
• Do you use the same imaging criteria as the main trial, or different ones, and why?
• Would a second scan with a different tracer, or a biopsy, add anything in my case?
• How recent does the scan need to be before the first infusion, and how long is mine considered valid?
• What do my kidney function and blood counts look like, and how do they affect the plan?
• What other treatment options are open to me now, including clinical trials, and how do they compare in what they aim to achieve?
• Which side effects should I plan for, and what can be done in advance about my teeth and mouth?
• How will you judge whether the treatment is working, and when will we decide about continuing?
• What radiation precautions will my household need to follow, and for how long?
• Who do I call, day or night, if something worries me between visits?

Consider taking someone with you and asking whether the appointment can be recorded or summarized in writing. A decision this consequential deserves more than one hearing.

When to call your doctor

Most people feel little from the scan and manage the treatment’s side effects at home. A small number of symptoms, however, should never wait for the next scheduled visit. They matter because the therapy lowers blood counts, because advanced prostate cancer can press on the spine, and because kidneys are working hard to clear the drug.

Call your care team the same day, or use the emergency number they gave you, if you notice any of the following:

• A fever, shaking chills or feeling suddenly unwell, which can signal infection when white cells are low.
• Unusual bruising, nosebleeds, bleeding gums, blood in urine or stool, or a rash of tiny red dots, which can indicate low platelets.
• Breathlessness at rest, a racing heart, chest pain or fainting, which may reflect severe anemia or another serious problem.
• New weakness, numbness or tingling in the legs, unsteadiness, or new trouble controlling bladder or bowel; these can indicate pressure on the spinal cord and are a medical emergency.
• Severe or rapidly worsening back or bone pain that does not respond to your usual pain relief.
• Vomiting that prevents you from keeping fluids down, or passing very little urine over a day.
• Confusion, extreme drowsiness or a sudden change in alertness.

Between infusions, also report persistent dry mouth that stops you eating, mouth ulcers, or steadily increasing fatigue, so the team can adjust supportive care and check your blood counts sooner. None of these symptoms means the treatment has failed; they mean the plan needs a doctor’s eyes today rather than next month. When in doubt, call. The people who know your scan and your blood results would far rather hear from you early.

Frequently asked questions

What is the success rate of lutetium 177 PSMA therapy?

There is no single success rate. In the main randomized trial of men with PSMA-positive advanced disease after hormonal therapy and chemotherapy, median survival was 15.3 months with treatment versus 11.3 months without, and about 46 percent saw PSA fall by half. Those are group averages in a selected population; individual results vary widely and cannot be predicted from the scan alone.

Is it okay to eat before a PSMA PET scan?

Usually yes. PSMA tracers do not rely on glucose metabolism, so most centers allow a light meal, unlike the fasting needed for FDG PET. Protocols differ, however, and some departments still restrict food or certain medicines for a few hours. Follow your own center’s instructions, and drink water freely unless told otherwise, since hydration improves image quality.

What are the potential pitfalls of a PSMA PET scan?

The main traps are normal tissues that glow (salivary glands, kidneys, bowel, nerve ganglia), tracer in the ureters imitating lymph nodes, benign bone conditions that take up tracer, and cancers that have shed PSMA and appear falsely quiet. Small deposits below a few millimeters can also hide. Experienced readers, the paired CT and clinical context reduce but do not eliminate these errors.

How accurate is a PSMA PET scan for prostate cancer?

Highly accurate compared with older imaging. A randomized trial in high-risk men before initial treatment found about 92 percent accuracy for PSMA PET/CT versus roughly 65 percent for CT plus bone scan. That study addressed staging, not response prediction, so before lutetium therapy the scan’s value lies in showing whether the target protein is present, not in guaranteeing benefit.

What does a PSMA PET scan show that a CT or bone scan cannot?

It shows biology rather than shape. CT and bone scans reveal size, structure and bone reaction; PSMA PET reveals whether cells at each site display the PSMA protein and how strongly. Small lymph nodes and early bone deposits that look normal on CT often glow on PSMA PET, and large deposits that fail to glow flag cancer that has changed character.

How recent does the PSMA PET scan need to be before lutetium therapy?

Teams generally want a scan taken close to the planned start, typically within a few weeks to a couple of months, because PSMA expression can change with disease progression or new hormone therapy. There is no universal cutoff; each center sets its own window. If your scan is older or treatment has changed since, ask whether a repeat is advised.

Who meets lutetium 177 PSMA therapy eligibility criteria?

In the trial evidence, men with metastatic castration-resistant prostate cancer who had already received an androgen receptor pathway inhibitor and taxane chemotherapy, whose PSMA PET met imaging criteria, and whose kidney function and blood counts were adequate. Some regions now allow earlier use. Fitness, other health conditions and personal priorities all factor into the treating team’s final decision.

What happens if my PSMA PET scan is negative?

A faint or negative scan in someone with active disease usually means the cancer is not displaying enough PSMA for the therapy to reach it. The team then discusses other options: further chemotherapy, different hormonal agents, treatments matched to tumor genetics, radiotherapy for symptoms, or clinical trials. Sometimes an FDG PET or biopsy is added to understand why the scan was quiet.

What PSMA PET scan preparation is needed on the day?

Expect a cannula, a tracer injection, a waiting period of roughly an hour while it distributes, emptying your bladder, then 20 to 45 minutes lying still in the scanner. Wear comfortable clothing without metal, bring your medicine list and any previous reports, and note when your hormone therapy last changed. Drink fluids afterward and follow brief contact precautions that day.

Is the radiation from a PSMA PET scan harmful?

The tracer contains a small amount of radioactivity that decays within hours and is comparable to other nuclear medicine tests. For someone already facing advanced cancer, the diagnostic benefit outweighs the small theoretical risk. Brief precautions around young children and pregnant contacts on the day are cautious good practice rather than a sign of danger, as general NHS PET guidance explains.

References

• Sartor O, et al. Lutetium-177–PSMA-617 for Metastatic Castration-Resistant Prostate Cancer (VISION). N Engl J Med. PubMed
• Hofman MS, et al. PSMA PET-CT in patients with high-risk prostate cancer before curative-intent surgery or radiotherapy (proPSMA). Lancet. PubMed
• NHS: PET scan
• MedlinePlus: Prostate Cancer

This article is for general information only and is not a substitute for professional medical advice. Please consult a qualified doctor about your individual situation.