Articles that explain laboratory results: what common blood and urine tests measure, what high or low values can mean and which questions to take to your doctor. A single number rarely tells the whole story; results are read together with your symptoms and history.
A high neutrophil count, called neutrophilia, usually means the body is responding to something: a bacterial infection, inflammation, physical stress, smoking, steroid medicines or…
Lymphocytes high on a blood test, called lymphocytosis, usually means your immune system is responding to something, most often a viral infection that will…
Leukocytosis means the white blood cell count on a blood test is higher than the laboratory's reference range, usually above roughly 11,000 cells per…
Parathyroid hormone (PTH) is made by four small glands in the neck and keeps blood calcium within a narrow range by drawing calcium from…
A BNP blood test measures B-type natriuretic peptide, a hormone the heart's pumping chambers release when they are stretched by pressure or fluid. In…
An elevated troponin level means heart muscle cells have released this protein into the bloodstream, but it does not always signal a heart attack.…
A high bilirubin level means the body is producing more bilirubin than the liver can process, or that processed bilirubin cannot drain through the…
The anion gap is a calculated value from a routine blood panel that reflects the balance of electrically charged particles in your blood. Most…
An A1C chart translates your hemoglobin A1C percentage into plain terms: below 5.7% is generally considered normal, 5.7% to 6.4% signals prediabetes, and 6.5%…
Blood urea nitrogen (BUN) measures how much urea nitrogen, a waste product of protein breakdown, is circulating in your blood. Healthy kidneys…
For most healthy adults, a basic blood panel every one to three years is reasonable, with cholesterol checked every four to six years starting…
At-home blood tests can be reasonably accurate for certain checks, such as cholesterol, average blood sugar, and some infection screens, when the sample is…
Low ferritin means the body's iron reserves are running down. Ferritin is a protein that stores iron, so a low blood level, often…
T4 (thyroxine) is the thyroid's main product, a stable hormone that circulates for about a week; T3 (triiodothyronine) is the shorter-lived, more potent active…
A progesterone test checks whether ovulation happened and how well the ovary's corpus luteum is working. "Day 21" is shorthand for the mid-luteal phase…
A CBC with differential measures red blood cells, hemoglobin, platelets, and total white blood cells, then breaks the white count into five types: neutrophils,…
The HbA1c test measures the percentage of hemoglobin in your red blood cells that is coated with glucose, which reflects your average blood sugar…
A TIBC (total iron-binding capacity) blood test measures how much iron your blood proteins, mainly transferrin, could carry. Read alongside serum iron…
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