Androstenedione and Estrone Dynamics in Hypothyroid Women*

Abstract

To examine the effects of hypothyroidism on androstenedione (A) and estrone (E1) metabolism, we infused eight women with [3H]androstenedione and [14C]estrone when they were hypothyroid and again when they were euthyroid after levo-T4 administration. MCRs and conversion ratios were measured using concentrations of radioactivity in the blood pools of A and E1. Peripheral aromatization was measured from the concentrations of radioactivity in the E1 glucuronide pool in the urine. After the women were euthyroid, the MCR of A had increased in seven of eight, the MCR of E1 increased in all eight, and peripheral aromatization had decreased in seven of eight. These findings indicate that hypothyroidism results in a decrease in the MCRs of A and E1 and, in most subjects, an increase in peripheral aromatization of A to E1.

Thyroid disorders and fertility

“…21 Also, reduction in metabolic clearance of androstenedione and estron may increase aromatization of peripheral estrogens. [22][23] Both these mechanisms and decrease in hemostasis factors regardless of these mechanisms may lead to symptoms such as infertility, menorrhagia and polymenorrhea in hypothyroidism. 4 There is no consensus over the TSH cut-off values which is a parameter that is used in diagnosis and classification.…”

Effect of levothyroxine treatment on in vitro fertilization and pregnancy outcome in infertile women with subclinical hypothyroidism undergoing in vitro fertilization/intracytoplasmic sperm injection

“…Hypothyroidism may affect the hypothalamic-pituitary-gonadal axis and the peripheral metabolism of sex steroids (1)(2)(3). Therefore, hypothyroidism may cause menstrual abnormalities, infertility, increased risk of miscarriage, obstetric complications, and adverse outcomes in offspring (3,4).…”

Effects of an Acute Water Load on Plasma ANP and AVP, and Renal Water Handling in Hypothyroidism: Comparison of Before and After L-Thyroxine Treatment.

“…Firstly, it is possible that the decreased metabolic clearance rate (MCR) of AVP may bring about the delayed disappearance of AVP from the blood in response to an acute water load and cause the decreased osmotic threshold for AVP release, thereby resulting in impaired formation of CH2o. Indeed, the MCR of circulating hormones has been reported to fall in hypothyroidism [14][15][16]. If this is the case, low plasma AVP in hypothyroid patients also suggests the presence of impaired AVP synthesis as well as its release, otherwise a fall in the MCR might increase plasma AVP.…”