Vitamin A

Pharm class: fat soluble vitamins

o   With high doses, erythrocyte and leukocyte counts may be decreased, and erythrocyte sedimentation rate (ESR) and prothrombin time (PT) may be increased.

Thiamin (Vitamin B1)

·      Lab values to monitor: May interfere with certain methods of testing serum theophylline, uric acid, and urobilinogen concentrations.

Riboflavin (Vitamin B2)

·      Lab values to monitor: May cause false elevations in urobilinogen and urinary catecholamine measurements.

Niacin (Vitamin B3)

o   When niacin is used as a lipid-lowering agent, serum cholesterol and triglyceride levels should be monitored prior to and periodically during therapy.

Pyridoxine (Vitamin B6)

o   May cause false elevations in urobilinogen concentrations.

Cyanocobalamin (Vitamin B12)

o   Monitor plasma folic acid, vitamin B12, and iron levels, hemoglobin, hematocrit, and reticulocyte count before treatment, 1 mo after the start of therapy, and then every 3–6 mo. Evaluate serum potassium level in patients receiving vitamin B12 for pernicious anemia for hypokalemia during the first 48 hr of treatment. Serum potassium levels and platelet counts should be monitored routinely during the course of therapy.

Vitamin C

o   May cause ↓ serum bilirubin and ↑ urine oxalate, urate, and cysteine levels.

Calcitriol (Vitamin D)

o   May cause false ↑ cholesterol levels.

Phytonadione (Vitamin K)

o   Monitor prothrombin time (PT) prior to and throughout vitamin K therapy to determine response to and need for further therapy.