TEXTBOOK PEDIATRIC GYNECOLOGY - 2013

Chapter 4. EXAMINATION METHODS IN PEDIATRIC GYNECOLOGY

DETERMINATION OF HORMONES AND THEIR METABOLITES IN BIOLOGICAL FLUIDS

The evaluation of the endocrine Reproductive System in girls involves measuring the concentrations of reproductive Hormones in Blood or urine.

To measure pituitary tropic hormones, Sex Hormones, and their metabolites, highly specific radioimmunoassays based on competitive binding are used. This method is highly sensitive and free of side effects, allowing for repeated serial testing.

The functional activity of the Gonads in both adults and children can be assessed by measuring the urinary excretion of 17-ketosteroids (17-KS) (Table 12).

Table 12. Hormones and their metabolites determined in urine and blood serum

When collecting 24-hour urine in children, It is important to remember that the first void of the morning must be discarded. All subsequent voids over the 24-hour period are pooled in a single refrigerated container.

When interpreting results, the patient's age and total body surface area must be taken into account. Taller and heavier girls generally show higher 17-KS excretion rates than the population average.

In prepubertal girls, 17-KS excretion is very low (2.5 mg per day), rising rapidly to adult levels during Puberty. 17-KS excretion also depends on Nutrition, gonadal activity, and sex. Nearly all conditions accompanied by hirsutism and virilization caused by adrenal dysfunction are characterized by elevated 17-KS excretion. Total urinary 17-KS levels exceeding 20 mg per 24 hours may indicate adrenal pathology.

Levels of 17-ketogenic steroids (17-KGS) in urine reflect the content of glucocorticoid metabolites. 17-KGS include cortisol, cortisone, and their reduced derivatives, almost all of which are of adrenal origin. Since 17-KGS also include pregnanetriol, the levels of these compounds increase in congenital adrenal hyperplasia.

In clinical conditions associated with impaired hepatic steroid conjugation or increased steroid excretion, free corticosteroids are measured for diagnostic purposes. In Cushing's syndrome, the determination of free urinary cortisol provides valuable diagnostic insight.