FRI430 A Case Of Elevated Sex Hormone-binding Globulin Secondary To Variegate Porphyria In A Patient With Hypogonadotropic Hypogonadism

Disclosure: J. Law: None. C. Yip: Research Investigator; Self; Eli Lilly & Company. Background: Acute porphyria is a group of disorders characterized by enzymatic defects in the heme biosynthetic pathway. The liver is the source of both acute intermittent porphyria (AIP) and variegate porphyria. AIP is known to cause an elevation in sex hormone-binding globulin (SHBG) levels, likely secondary to impaired hepatic function and hepatocyte abnormalities(1). We describe a case of elevated SHBG secondary to variegate porphyria, in a male with hypogonadotropic hypogonadism. Case Report: A 44-year-old male presented with an elevated SHBG and symptoms of hypogonadism with low libido, weakness, and fatigue. Fasting morning bloodwork revealed an elevated SHBG at 89 nmol/l (13.5- 71.0), a normal total testosterone level at 12.95 nmol/l (8-32), and a low bioavailable testosterone at 0.82 nmol/l (2.5-10), with confirmatory repeat blood work. His history was significant for longstanding variegate porphyria, manifesting as frequent attacks of abdominal pain. He was on opioids for greater then 10 years for his chronic pain, as well as metoclopramide. On assessment of causes for his elevated SHBG, his TSH was normal at 1.49 mIU/L (0.35-4.30). He did not have cirrhosis, hepatitis, hereditary hemochromatosis, and was not on anticonvulsants. No other cause was found, and his elevated SHBG was deemed secondary to his variegate porphyria. His normal total testosterone level was due to his elevated SHBG, but as mentioned, his bioavailable testosterone was low. His LH and FSH were both inappropriately normal, with his LH being 4.67 IU/L (0.6-12.0) and his FSH 4.7 IU/L (1.0-12.0), in keeping with hypogonadotropic hypogonadism. He went through normal pubertal development and had no anosmia. Workup revealed an elevated prolactin level of 73.8 ug/l (3.5-19.4). He had no galactorrhea or gynecomastia and an MRI sella revealed a normal pituitary gland. His elevated prolactin level was determined to be secondary to his opioid medication and/or metoclopramide use. His hypogonadotropic hypogonadism was deemed secondary to his opioid medications and/or hyperprolactinemia. Conclusion: This case demonstrated variegate porphyria as a likely cause of elevated SHBG, similar to AIP. In patients with variegate porphyria and symptoms of hypogonadism, the SHBG should be measured and if it is elevated, the bioavailable or free testosterone levels should be used in assess instead of relying on the total testosterone levels. As has been previously shown, this case also illustrated the use of opioid medications as a cause of hypogonadotropic hypogonadism. References: (1) Herrick AL, McColl KE, Wallace AM, Moore MR, Goldberg A. Elevation of hormone-binding globulins in acute intermittent porphyria. Clin Chim Acta. 1990 Feb 28;187(2):141-8. doi: 10.1016/0009-8981(90)90340-x. PMID: 2107988. Presentation: Friday, June 16, 2023