(20.11) Double Trouble!: A Case of Idiopathic Hypoparathyroidism and Fahr Syndrome

Primary hypoparathyroidism is described as hypocalcemia due to inadequate parathyroid hormone (PTH). Rare causes of hypoparathyroidism include autoimmune damage to parathyroid glands, altered regulation of PTH, abnormal parathyroid gland development, or impaired PTH activity. Brain calcifications can be found in some hypocalcemic patients. Fahr syndrome is characterized by calcium deposition in different brain areas, including basal ganglia, dentate nuclei, cerebral cortex, and other brain structures. Based on the etiology, primary Fahr's is defined as familial or sporadic, while secondary is associated with endocrinopathies and others causes. Our case describes a patient with idiopathic hypoparathyroidism with intracranial calcifications - Fahr syndrome.

Case(s) Description :

We present a case of a 37-year-old patient with a medical history of hypocalcemia, bipolar disorder, focal seizures, and cocaine and marijuana use. She came to our institution due to a focal seizure, perioral numbness, and hand and feet paresthesias. There was no family history of parathyroid or calcium disorders, immunodeficiencies, or endocrine disorders. The patient had no history of neck surgery or head trauma. Initial laboratory demonstrated ionized calcium of 0.67mmol/L (Reference: 1.12-1.32), phosphate 5.5mg/dl (Reference: 2.5-4.5mg/dl), and PTH 4.8 pg/ml (Reference: 15-65pg/ml). Findings were consistent with hypoparathyroidism. Morning cortisol was 7.8 mcg/dl and 24 urine calcium 400mg/24h. EKG demonstrated QT prolongation. Head CT w/o contrast and brain MRI showed basal ganglia, thalami, and cerebellar dentate nuclei calcifications consistent with Fahr disease. The patient was admitted and treated with IV calcium gluconate and calcitriol, which improved symptoms. IV calcium was switched to oral calcium carbonate replacement. At the end of the hospitalization, improvement in neuromuscular symptoms and ionized calcium was noted. A specific cause for hypoparathyroidism was not found, for which the presumed diagnosis of idiopathic primary hypoparathyroidism was attributed. Due to patient limitations and unwillingness to follow up, genetic testing was not conducted to confirm a pathogenic mutation definitively.

Discussion :

There is not much data on the incidence and prevalence of Fahr syndrome. Some authors suggest a very low prevalence (< 1 per million population). Treatment of underlying conditions like hypoparathyroidism has shown to improve the symptoms. Idiopathic hypoparathyroidism and secondary Fahr syndrome are rare, and it is essential to understand and identify such conditions to assist in the early diagnosis and treatment of such patients.