A Chem-20 is a comprehensive chemistry panel of about 20 blood tests. It typically includes electrolytes (sodium, potassium, chloride, bicarbonate/CO2), renal function (BUN, creatinine), glucose, calcium, magnesium, phosphorus, liver enzymes (AST, ALT, alkaline phosphatase), bilirubin, total protein and albumin (± globulin), and other chemistry markers such as anion gap; exact components vary by laboratory and order set.

A chem‑20 is a broad blood chemistry panel measuring about 20 analytes—electrolytes, glucose, kidney and liver function markers, proteins and lipids—so it’s more extensive than basic chemistry panels. However, it is not fully comprehensive: it omits many specialized tests (hormones, infectious serology, vitamins, tumor markers) and certain diagnostics. Clinical context and symptoms determine if further testing is needed.

Fasting is not uniformly required for a chem-20. Many chemistry panel components (electrolytes, kidney and liver tests) don’t need fasting, but if the panel includes fasting glucose or a lipid test, your provider may ask for an 8–12 hour fast. Always follow the lab or clinician’s instructions, since specific test orders determine fasting needs.

A chemistry (chem) blood test measures chemicals and electrolytes in blood to assess metabolic and organ function. Common panels include the basic metabolic panel (glucose, sodium, potassium, chloride, bicarbonate, BUN, creatinine, sometimes calcium) and the comprehensive metabolic panel (also liver enzymes and proteins). It evaluates kidney and liver health, blood sugar and electrolyte balance, and monitors treatments.

A Chem 20 is a broad blood chemistry panel measuring about 20 analytes—electrolytes (sodium, potassium, chloride), kidney markers (BUN, creatinine), glucose, liver enzymes and bilirubin, proteins and albumin, minerals (calcium, magnesium, phosphorus), and other metabolic markers. It assesses overall metabolic and organ function, aids diagnosis and monitoring, and the exact tests included can vary by laboratory and clinical need.

You usually don’t need to fast for a routine chem‑20 panel, but if the panel includes glucose or lipid measurements your clinician or lab may ask for an 8–12 hour fast for accurate results. Drink water, continue essential medications unless told otherwise, and confirm fasting instructions with the ordering provider or lab before the test.