PSAT217 Estrogen Deficiency as a Cause of Decreased 1- alpha - hydroxylase Activity

CASE DESCRIPTION: A 40 year old woman receiving cholecalciferol therapy -10,000 IU, and alfacalcidol 1 mcg per day showed a 25 (OH) D increase to 351. 1 ng/mL (normal 65-100) with a normally high parathormone level of 33.5 pg/mL (normal 15-65). Clinically, symptoms of vitamin D deficiency - decreased immunity, decreased muscle mass and strength, depression, and symptoms of estrogen deficiency (hot flashes, scanty menstruation, hair loss) persisted against a high 25(OH)D background, so estrogen determination was performed in the steroid profile of saliva. Estradiol content was decreased - 3.45 pg/ml (norm 4.17 - 9.28), in connection with which transdermal estrogen therapy in a dose of 3.0 g was prescribed. Against the background of estrogen therapy, parathormone decreased from 33.5 to 22.4 pg/ml. Determination of 25(OH)D and estradiol in saliva was performed by mass spectrometry, determination of parathormone by ELISA. DISCUSSION: Vitamin D status depends on several factors, in particular on the activity of the enzyme 1 - alpha-hydroxylase (CYP27B1) in the kidney, which converts 25 (OH) D into the active form (1,25 - (OH)2 - D), which in turn depends on both parathormone and sex steroids (estrogen and androgens), determination of which is not a routine practice in vitamin D deficient patients. Elevated parathormone levels are considered a marker of vitamin D deficiency (secondary hyperparathyroidism). Decreased parathormone levels are considered a laboratory manifestation of vitamin D overdose. In this patient, there was no decrease in parathormone below the differential level of 25(OH)D in the background of high levels. Sex steroids increase the synthesis of calcitriol (D hormone, dihydrocholecalciferol 1,25 - (OH)2 - D) by activating the enzyme 1 - alpha - hydroxylase (CYP27B1) in the kidneys. In particular, estradiol deficiency exacerbates vitamin D deficiency. CONCLUSION: Determination of 25(OH)D levels in patients with decreased 1 -alpha-hydroxylase activity leads to hypodiagnosis of vitamin D deficiency. In all patients with high 25(OH)D levels, the determination of parathormone as well as estrogens in saliva is necessary. Presentation: Saturday, June 11, 2022 1:00 p.m. - 3:00 p.m.