1. INTRODUCTION
Postoperative permanent hypoparathyroidism is characterized by hypocalcemia, hyperphosphatemia, and low to inappropriately normal parathyroid hormone levels, which persist more than six months after surgery.1 It occurs in 0.3% to 5.1% of individuals who undergo thyroid surgery for thyroid cancer.2-4Severe hypocalcemia can present with carpopedal spasms, tetany, seizures, and cardiac dysrhythmias. Longstanding postoperative hypoparathyroidism is characterized by intracranial calcifications of basal ganglia and cerebellum; calcifications beyond these areas are rare.1,5 We report the case of a 56-year-old lady who presented with carpopedal spasms, tetany, generalized tonic-clonic seizure, and extensive bilateral brain calcifications due to postoperative permanent hypoparathyroidism.
2. CASE REPORT
A normotensive, nondiabetic 56-year-old lady, who had undergone near-total thyroidectomy for papillary carcinoma of thyroid 20 years ago, presented in the emergency department with history of spasms in her hands and calves, followed by sustained contraction of hand muscles. Then she had an episode of tonic-clonic generalized abnormal body movements with uprolling of eyes and frothing from mouth, which lasted about 30-35 seconds; it was followed by a brief period of confusion and amnesia. She had been taking calcium, vitamin D, and hormonal supplements for hypothyroidism after the surgery until five months ago when she stopped taking them due to her general good condition. Four months ago, she experienced episodes of calf spasms, which lasted about five minutes and were severe enough to limit walking. On seeking medical care, the episodes were attributed to calcium deficiency, and she was prescribed calcium and cholecalciferol. She had undergone cataract surgery eight years ago. She had no history of fever, headache, vomiting, palpitation, or chest pain.
On examination, the patient had positive trousseau’s sign on tourniquet test, which manifested as carpopedal spasm: flexion of the wrist and metacarpophalangeal joints, extension of the interphalangeal joints, and adduction of the thumb. She had an old, transverse post-surgical scar on her neck. Ophthalmological evaluation revealed an intraocular lens implant in each eye. There was no pallor, icterus, clubbing, or lymphadenopathy. Her respiratory, cardiovascular, abdominal, and neurological examinations were unremarkable.
Laboratory investigations revealed the following findings: corrected serum total calcium, 1.25 mmol/L (normal range, 2.1-2.6); serum phosphorus, 2.19 mmol/L (normal range, 0.8-1.54); Intact Parathyroid Hormone (IPTH), 5.2 ng/L (normal range, 7.5-53.5); 25-hydroxyvitamin D, 112.07 nmol/L (normal range, 74.88-249.6); magnesium, 0.53 mmol/L (normal range, 0.69-1.02); serum albumin, 39 g/L (normal range, 38-49); Alkaline Phosphatase (ALP), 221 U/L (normal range, 90-306); free T3, 3.05 pmol/L (normal range, 4.26-8.1); free T4, 28.3 pmol/L (normal range, 10.2-28.2); Thyroid Stimulating Hormone (TSH), 0.31 mU/L (normal range, 0.46-4.68); serum sodium, 138 meq/L (normal range, 135-145); and potassium, 5.1 meq/L (normal range 3.5-5). Her ECG showed normal sinus rhythm with no QT interval prolongation.
Computed tomography of the brain revealed extensive bilateral calcifications involving basal ganglia, thalami, periventricular region, subcortical fronto-pareito-occipital region, and cerebellum (Figure 1).
The patient was treated with intravenous calcium gluconate, calcitriol, and magnesium. Serum calcium and magnesium levels were checked daily. After four days of intravenous calcium treatment, total calcium rose to 2.1 mmol/L. Her spasms subsided, and seizure did not recur. On the fifth day, intravenous calcium was replaced by oral calcium. She was discharged on 1500 mg of oral calcium and 1 mcg of oral calcitriol daily.
The patient was explained about the appropriate supplements and advised to follow up every three months. She followed up on the third month of discharge. She had strictly adhered to the treatment regimen and had not experienced seizure or spasm again; her total calcium level was 2.15 mmol/L (normal range, 2.1-2.6).