Endocrine Abstracts

Introduction: Hypercalcaemia is a commonly encountered biochemical abnormality. The most common causes of hypercalcaemia are primary hyperparathyroidism and malignancy. Familial Hypocalciuric Hypercalcaemia (FHH) is a rare cause of hypercalcaemia.

Case: We present a 53-year-old female, who was referred to the endocrinology clinic for further investigation of a persistent hypercalcaemia associated with low-to-normal parathyroid hormone level (1.5pmol/l). She suffered from chronic anergia, generalised myalgia and recurrent renal stones. There was a significant family history; her father, brother, sister and grandson were also known to have hypercalcaemia. Prior to her endocrinology referral, she was managed by the urology team for recurrent renal stones for several years. She was extensively investigated for secondary causes of hypercalcaemia, including malignancy. The patient had a myeloma screen; a CT scan of her thorax, abdomen and pelvis; and serum ACE levels (14.2 nmol/L). There were no positive findings. Ultrasound scans of her parathyroid and thyroid glands were suggestive of an atypical and equivocal right inferior parathyroid adenoma. A sestamibi scan was conducted, which showed appearances were most likely due to adenomatous hyperplasia of the parathyroid rather than a solitary adenoma. Finally, after genetic testing came back positive, a diagnosis for FHH type 1 was made.

Discussion: FHH is a rare cause of hypercalcaemia and is almost always asymptomatic. It should be suspected in any patients with a strong family history of hypercalcaemia. This is an exceptional case where the patient, who has had FHH confirmed after genetic testing, has been symptomatic with recurrent renal stones and osteopenia.

Conclusion: Patients with FHH are known to be asymptomatic. We have demonstrated a unique case of symptomatic FHH, with associated end-organ damage. The possibility of dual pathology should be explored. Thus the case has been referred to a tertiary centre for further investigation.