Delayed Diagnosis of Pseudohypoparathyroidism with Secondary Fahr Syndrome in Adulthood: A Case Report

Secondary Fahr syndrome is a rare entity characterized by the presence of abnormal calcifications in the basal ganglia and cerebral cortex, and has been linked with endocrine disorders particularly parathyroid and vitamin D disturbances. Herein we report a case of pseudohypoparathyroidism (PHP) in an adult presenting with frequent episodes of recurrent seizures and spasms of hands and feet.

Case Description:

A 21-year-old male referred from neurology department to endocrine clinic with recurrent seizures that were uncontrolled despite treatment with anti-epileptic medications and frequent episodes of tetanic spasms of hands and feet for last 8 years. Family history was negative of seizures, thyroid or calcium disorders. He did not have intellectual disability.

Physical examination showed normal vital signs; Trousseau's sign was positive whereas Chvostek's sign and dysmorphic features suggesting Albright hereditary osteodystrophy (AHO) were absent.

Laboratory investigations revealed hypocalcemia of 7.6 mg/dl ( 8.6-10.2 ), hyperphosphatemia of 6.1 mg/dl ( 2.5-4.5) with elevated PTH 727.00 pg/ml( 10-65), normal renal function and urinary calcium excretion, normal serum albumin and normal 25 OH Vitamin D level. Thyroid function tests revealed subclinical hypothyroidism with mild elevation of TSH and FT4 in normal range, suggestive of partial TSH resistance. Urinary cyclic adenosine monophosphate level and Gsα subunit assay were not available. CT scan of the brain showed extensive coarse calcifications involving bilateral basal ganglia and grey white junction with in both the cerebrum and cerebellum likely due to pseudohypoparathyroidism resulting in secondary Fahr’s syndrome.

Considering laboratory findings and absence of AHO phenotype, partial resistance to thyroid hormones was considered as possible and a PHP type 1b as more likely. He was treated with calcium carbonate, cholecalciferol, calcitriol and levetiracetam with subsequent improvement in symptoms and normalization of calcium and phosphorus levels.

Discussion:

In this case, our patient presented with epileptic seizure, extensive brain calcification, and hypocalcemia. Such clinical scenario should prompt diagnostic evaluation for PHP as a treatable cause of seizures.

Our patient was diagnosed with PHP in adulthood, even though this is an inherited disorder with early clinical onset and this proves that there are shortcomings in the diagnostic approach to patients with hypocalcemia.

Hypocalcemia, hyperphosphatemia and elevated PTH with normal renal function are findings that confirm PHP.

Although its strict classification requires genetic studies, the phenotype and the profile of the associated hormonal resistance allow a first approximation.

Therefore, it is essential to rule out a calcium disorder in all patients with convulsive syndrome or calcifications in the basal ganglia.