Examples of Patient Variables That
May Affect Chemistry Values
Clinical Chemistry Review 69
VARIABLE ANALYTES AFFECTED
Diurnal variation ↑in am: ACTH, cortisol, iron
↑in pm: growth hormone, PTH, TSH
Day-to-day variation ≥20% for ALT, bili, CK, steroid hormones, triglycerides
Recent food ingestion ↑glucose, insulin, gastrin, triglycerides, Na+, uric acid, iron, LD, Ca2+; ↓chloride, phosphate, K+
Fasting required: fasting glucose, triglycerides, lipid panel
Alcohol ↓glucose; ↑triglycerides, GGT
Posture ↑albumin, cholesterol, Ca2+when standing
Activity ↑in ambulatory patients: creatinine kinase (CK)
↑with exercise: K+, phosphate, lactic acid, creatinine, protein, CK, AST, LD
Stress ↑ACTH, cortisol, catecholamines
Age, gender, race, drugs Various