Background: Creatinine Correction in Urinary Hormone Testing
Urinary hormone concentrations can vary due to hydration status. To standardize for this variability, results are corrected to urinary creatinine levels (e.g., ng/mg creatinine). This assumes that creatinine excretion is relatively stable — a condition not always met in the presence of proteinuria or renal impairment.
Urine specimens with creatinine levels below and above the reportable range of 0.05-16.02 mg/mL will be designated as Test Not Performed (TNP). Associated panels will also be marked as TNP and a retest would be requested. All tests with urine creatinine between 0.05-16.02mg/mL will be processed and included in the final patient reports.
Impact on Specific Hormones in the Hormone Zoomer Panel
Adrenal Hormones & Cortisol Metabolites
These metabolites are water-soluble and highly dependent on renal clearance. Proteinuria can lead to either accumulation or excessive loss, skewing their levels post-creatinine correction.
Androgens
Androgens are less water-soluble than adrenal steroids, but many of their metabolites are excreted renally. In proteinuria, distortion in creatinine-normalized values may over- or underestimate true androgenic activity.
Estrogens & Estrogen Metabolites
Many estrogen metabolites are conjugated and excreted via urine. Proteinuria can affect conjugation or deconjugation enzymes in renal tissue, altering metabolite profiles.
Progesterone Metabolites
Progesterone metabolites are lipophilic but still partially renally excreted. Creatinine correction in proteinuric states may misrepresent progesterone metabolite balance.
Melatonin & Oxidative Stress Marker (8-OHdG)
Melatonin is typically measured as 6-sulfatoxymelatonin in urine — renal impairment or proteinuria affects its clearance. 8-OHdG, a DNA damage marker, is also filtered renally and may accumulate if proteinuria disrupts tubular excretion.
Endocrine Disruptors
These xenobiotics are usually conjugated in the liver and excreted renally. Clearance or altered filtration dynamics in proteinuria can result in erratic urinary levels especially after creatinine normalization.
Best Practices for Interpretation
Consider combining urine hormone testing with serum hormone testing, with comparison of findings correlated with clinical and other diagnostic information.