Status epilepticus caused by hypocalcaemia in a 6-month old child with hypoparathyroidism

Aim: To present consequence of hypocalcaemia in a child with status epilepticus at the age of 6 months.

Methods: Case presentation and analysis of clinical data.

Results: The child was born after uneventful pregnancy at term and without family history of seizures. At the age of 6 months he presented with status epilepticus (SE), which only could be interrupted with cumulative 0, 17 mg/kg lorazepam intravenously after 90 minutes. Inflammatory process as reason for status epilepticus could be excluded and cerebral ultrasound was without pathological findings. Long-term treatment with oral phenobarbital (4, 6 mg/kg/d) was started. By laboratory testing hypocalcaemia (0.72 mmol/L ionized) and hypoparathyroidism (12.4 ng/L) could be detected as reason for SE. Substitution of vitamin D3 lead to increasing calcium-excretion in urine. This was suspicious for a gain-of-function mutation of calcium sensing receptor, which could be proved by genetic molecular testing (c.2483C > A). This resolves in severe hyperparathyroidism with hypocalcaemia, hyperphosphatemia, and subsequently epileptic seizures. Medical treatment with vitamin D3, calcium carbonate, and hydrochlorothiazide stabilized calcium in serum in this patient at a low level. Nevertheless no normalization of calcium could be reached and electroencephalogram (EEG) presented generalized epileptic activity. At the age of 11 months another prolonged generalized seizure was provoked by fever (calcium ionized 0.7 mmol/L). Continuous subcutaneous infusion of recombinant parathormone as treatment option is discussed.

Discussion and Conclusion: In this case gain-of-function mutation of calcium sensing receptor could be detected as reason for hypocalcaemia and SE. EEG is characterized by generalized slowing and generalized epileptic activity in case of considerable hypocalcaemia causing prolonged epileptic seizures. Vitamin D3 and oral substitution can stabilize calcium in serum at a low level but because of another SE further causal approved treatment in this patient is needed.