Educational guides to clinical biochemistry, metabolism, enzymes, proteins, electrolytes, and biochemical testing concepts.
Dig into the electrolyte and metabolic panels that reveal how your body is really functioning.
Start Here →Osmolality vs osmolarity describes two closely related ways of expressing how concentrated a solution is. Osmolality is the number of dissolved particles per kilogram of solvent, while osmolarity is the number of dissolved particles per litre of solution. In clinical laboratories, measured serum or plasma osmolality is usually preferred because it is determined directly by … Read more
Calcium vs ionised calcium compares total calcium in blood with the fraction that is free and biologically active. A routine total calcium test measures ionised calcium plus calcium bound mainly to albumin and calcium complexed with other molecules. An ionised calcium test measures only the unbound fraction. Total calcium is easier and more commonly measured, … Read more
Free vs total PSA compares two ways of measuring prostate-specific antigen in blood. Total PSA includes PSA circulating in a free form plus PSA bound to certain blood proteins, while free PSA measures only the unbound fraction. Laboratories can also calculate percentage free PSA by comparing free PSA with total PSA. The comparison may add … Read more
Troponin vs CK-MB compares two blood markers released after muscle injury. Cardiac troponin I or T is much more specific to heart-muscle injury and is the preferred biomarker in modern assessment of suspected myocardial infarction. CK-MB is an isoenzyme of creatine kinase that is relatively enriched in heart muscle but is also influenced by skeletal … Read more
Venous vs arterial blood gas compares blood taken from a vein with blood taken from an artery for rapid assessment of acid–base status and respiratory physiology. A venous blood gas (VBG) is easier to collect and can often provide useful information about pH, carbon dioxide and bicarbonate. An arterial blood gas (ABG) is more invasive … Read more
Lactate vs pyruvate compares two closely linked products of glucose metabolism. Pyruvate is formed at the end of glycolysis and can enter mitochondrial energy pathways when conditions allow. Lactate is produced from pyruvate through lactate dehydrogenase, helping regenerate NAD⁺ so glycolysis can continue. Blood lactate is commonly measured in acute care, while pyruvate and the … Read more
TSH vs free T4 compares the pituitary signal that regulates the thyroid with one of the main thyroid hormones circulating in blood. TSH is produced by the pituitary gland and tells the thyroid how strongly to produce and release thyroid hormones. Free T4 measures the unbound fraction of thyroxine available to tissues. Doctors often interpret … Read more
The anion gap blood test is usually not a separate test requiring its own blood draw. It is a calculated value derived from electrolytes already measured in a blood sample, mainly sodium, chloride and bicarbonate. The calculation estimates the difference between selected positive and negative ions and can help clinicians assess acid–base balance, particularly when … Read more
ALT vs AST compares two enzymes commonly measured in blood tests used to assess possible liver-cell injury. ALT, or alanine aminotransferase, is found mainly in the liver, while AST, or aspartate aminotransferase, is also present in substantial amounts in muscle and other tissues. Doctors therefore interpret the two values together and alongside bilirubin, alkaline phosphatase, … Read more
Creatinine vs eGFR Creatinine vs eGFR: What’s the Difference and What Do Your Results Mean? Creatinine vs eGFR compares a measured blood marker with a calculated estimate of kidney filtration. Serum creatinine is a waste product generated mainly from normal muscle creatine metabolism and measured directly in a blood sample. Estimated glomerular filtration rate (eGFR) … Read more