Pituitary glycoprotein hormone alpha-subunit secretion by cirrhotic patients

RESUMO

Secretion of the alpha-subunit of pituitary glycoprotein hormones usually follows the secretion of intact gonadotropins and is increased in gonadal failure and decreased in isolated gonadotropin deficiency. The aim of the present study was to determine the levels of the alpha-subunit in the serum of patients with cirrhosis of the liver and to compare the results obtained for eugonadal cirrhotic patients with those obtained for cirrhotic patients with hypogonadotropic hypogonadism. Forty-seven of 63 patients with cirrhosis (74.6 percent) presented hypogonadism (which was central in 45 cases and primary in 2), 7 were eugonadal, and 9 women were in normal menopause. The serum alpha-subunit was measured by the fluorimetric method using monoclonal antibodies. Cross-reactivity with LH, TSH, FSH and hCG was 6.5, 1.2, 4.3 and 1.1 percent, respectively, with an intra-assay coefficient of variation (CV) of less than 5 percent and an interassay CV of 5 percent, and sensitivity limit of 4 ng/l. The serum alpha-subunit concentration ranged from 36 to 6253 ng/l, with a median of 273 ng/l. The median was 251 ng/l for patients with central hypogonadism and 198 ng/l for eugonadal patients. The correlation between the alpha-subunit and basal LH levels was significant both in the total sample (r = 0.48, P<0.01) and in the cirrhotic patients with central hypogonadism (r = 0.33, P = 0.02). Among men with central hypogonadism there was a negative correlation between alpha-subunit levels and total testosterone levels (r = 0.54, P<0.01) as well as free testosterone levels (r = -0.53, P<0.01). In conclusion, although the alpha-subunit levels are correlated with LH levels, at present they cannot be used as markers for hypogonadism in patients with cirrhosis of the liver