Creatinine clearance reflects the glomerular filtration rate, the ability of kidneys to filter waste products. Moderate decrease in renal function is detected by creatinine clearance. It also monitors progression of renal disease.
Urinary porphobilinogen is the first step in the diagnosis of Acute intermittent porphyria. An acute attack usually leads to gastrointestinal disturbance and neuropsychiatric disorders.