Creatine

Creatine is synthesized in the liver, taken up by muscle for stored energy as creatine phosphate, and broken down to creatinine; it then enters the circulation and is excreted by the kidneys.

Normal range:

Male: 0.2 " “0.7 mg/dL

Female: 0.3 " “0.9 mg/dL

Use

Serum creatine levels may be significantly increased in amyotrophic lateral sclerosis, dermatomyositis, myasthenia gravis, starvation, muscular dystrophies, and trauma. Creatine synthesis is stimulated by methyltestosterone and may also be increased in hyperthyroidism, diabetic acidosis, and puerperium.

This test is rarely used clinically.

Interpretation

Increased In

High dietary intake (meat)

Destruction of muscle

Hyperthyroidism (this diagnosis is almost excluded by normal serum creatine)