SUN-503 Hyperparathyroidism and Turner Syndrome: A Rare, Overlooked Association?

Background: Primary hyperparathyroidism (PHPT) is a relative common endocrine disease, affecting typically postmenopausal women. Turner syndrome (TS) promotes an hypogonadal state starting usually since adolescence and it is not reported a higher risk of PHPT in TS, although a few case reports were published throughout the years. Here we present two cases of PHPT concurrent with TS in women less than 50 years of age. Clinical cases: The first case is a 20-year-old women with karyotype 45,X developed nephrolithiasis needing urological intervention with normal calcium levels. After two years of follow-up, despite an adequate estrogen replacement, her bone densitometry showed a 9.1% bone loss in total hip and she had new episodes of nephrolithiasis. Her laboratory work-up revealed a serum calcium level of 10.9mg/dL (normal values 8.6-10.0mg/dL), phosphorus level of 3.6 mg/dL (normal values 2.5-4.8mg/dL), PTH level of 78.6pg/mL (normal values 14-72pg/mL) and 25-hydroxivitamin D levels of 19ng/mL. Her neck ultrasound revealed a hypoechoic nodule with 24x10x9mm behind the right thyroid lobe compatible with an enlarged parathyroid. The second case is a 40-year-old women with karyotype 45,X who was only diagnosed with TS at 37 years despite primary amenorrhea. She has type 2 diabetes and poor compliance to her medications, including estrogen replacement. During follow-up, she developed asymptomatic nephrolithiasis detected during abdominal ultrasound to assess hepatic periportal fibrosis. Her bone densitometry shows progressive bone loss. Her laboratory work-up showed an elevated serum calcium (11.1mg/dL), normal phosphorus (3.4mg/dL), an inappropriate normal PTH (50.1pg/mL), normal 25-hydroxivitamin D (21.8ng/mL). Her neck ultrasound revealed a hypoechoic nodule with 8mm behind the right thyroid lobe and parathyroid scintigraphy with Sestamibi corroborates this image as an enlarged parathyroid gland. Conclusion: PHPT is an unusual diagnosis before 50 years of age and can aggravate the bone loss caused by the hypogonadal state in TS. Here, we present two cases of young women with PHPT and TS, which may be a rare and often undiagnosed association.