LETTER TO EDITOR
Year : 2001 | Volume
: 11 | Issue : 4 | Page : 222--223
H Singh, P Muthaiah
Department of Radiodiagnosis, Command Hospital (Southern Command) Pune 411040, India
Department of Radiodiagnosis, Command Hospital (Southern Command) Pune 411040
|How to cite this article:|
Singh H, Muthaiah P. Idiopathic hypoparathyroidism.Indian J Radiol Imaging 2001;11:222-223
|How to cite this URL:|
Singh H, Muthaiah P. Idiopathic hypoparathyroidism. Indian J Radiol Imaging [serial online] 2001 [cited 2020 Jul 5 ];11:222-223
Available from: http://www.ijri.org/text.asp?2001/11/4/222/28411
Idiopathic hypoparathyroidism is an uncommon condition of unknown etiology. Established criteria for its diagnosis are a) low serum calcium b) high serum inorganic phosphates c) renal insufficiency, steatorrhea, chronic diarrhea and alkalosis must not be present and rickets and osteomalacia must be excluded. In hereditary and acquired hypoparathyroidism, parathyroid hormone (PTH) is either undetectable or in the normal range, and this finding in a hypocalcemic patient is supportive of hypoparathyroidism, as distinct from ineffective PTH action, in which even mild hypocalcemia is associated with elevated PTH levels. Hence a failure to detect elevated PTH levels establishes the diagnosis of hypoparathyroidism, elevated levels suggest the presence of secondary hyperparathyroidism which is more common  .
A forty-year-old man presented with spasmodic contractions of upper and lower limbs of the left side, giddiness and ataxic gait of five years duration. The symptoms were insidious in onset and progressive in nature. The frequency of the spasmodic contractions, which occurred once a fortnight gradually increased in frequency to 2-3 times a day lasting for 30-60 seconds. He had no history of injury or surgery, diabetes or hypertension.
On examination, his face was expressionless and rounded [Figure 1]. He had features of dementia, dysarthria, dystonia and postural instability. Cerebellar signs were positive in the form of ataxia and past pointing. Carpopedal spasm was present. Trousseau's and Chovstek's signs were positive. There were no neurocutaneous markers. He had left VII nerve palsy and his deep tendon reflexes were reduced bilaterally. He had bilateral cortical cataract.
Biochemical analysis revealed hypocalcemia (6.5 mg%), hyperphosphatemia (6.6 mg%) and PTH level was within normal limits (31.2 pgm/ml). 24-hour urinary calcium was reduced (112 mg/24 hours). Serum electrolytes, blood urea and creatinine levels were within normal limits. ECG showed a prolongation of QT interval (0.56 seconds).
Lateral radiograph of the skull showed faint parietal calcification and that of the pelvis showed calcification of the iliolumbar and sacrospinous ligaments [Figure 2]. CT scan of the head showed extensive intracranial calcification in the dentate nucleus [Figure 3] and basal ganglia [Figure 4] having CT value of 300-400 HU. Scattered calcification was seen in left temporal, fronto-parietal and occipital lobes. Frontoparietal gyral calcification was also seen [Figure 5]. With these clinical, biochemical and radiological features, a diagnosis of hypoparathyroidism was made and was treated with calcium and 1-alpha (OH) vitamin D-3. On follow up examination, the patient showed clinical improvement in the form of regression of his spasmodic contractions and improved biochemical parameters with serum calcium increased to 8.2 mg% and phosphates reduced to 4.7 mg%.
The signs and symptoms of hypoparathyroidism are those of hypocalcemia resulting in increased neuromuscular excitability manifesting as tetany, paresthesia, seizures, organic brain syndrome or calcium deposition in the form of cataract or intra cranial calcification  . However in this case there was very extensive intracranial parenchymal calcification including that of dentate nucleus and basal ganglia.
The classic patient with hypoparathyroidism has a rounded expressionless face as seen in this patient, is shorter than average and sometimes dwarf like, and may have cataract. Dental hypoplasia and aplasia develop depending upon the patient's age at the time of onset of hypoparathyroidism. Basal ganglia calcification and extrapyramidal syndromes are more common and earlier in onset, in Idiopathic hypoparathyroidism. Pseudohypoparathyroidism, an example of ineffective parathormone action rather than a failure of parathyroid gland production, shares several features with hypoparathyroidism  .
Hypocalcemia triggers the neuromuscular excitability, which characterizes hypoparathyroidism. Tetany may then develop with numbness, cramps, carpopedal spasm, laryngeal stridor and generalized convulsions. If untreated for years, mental retardation may result  . Lower degrees of neuromuscular excitability may result in latent tetany, which is elicited by testing for Chovstek's and Trousseau's signs. Chovstek's sign is produced by tapping the skin over the facial nerve anterior to the external auditory meatus and consists of ipsilateral contraction of the facial muscles. Trousseau's sign is produced by creating ischemia of nerves in the upper arm, usually by inflating a sphygmomanometer to 20 mm Hg above the systolic blood pressure for 3-5 minutes. The result is thumb adduction, metacarpophalangeal joint flexion and interphalangeal joint extension.
Hypocalcemia lowers the excitation threshold for pre-existing sub-clinical epilepsy. On an ECG, prolongation of QT interval is a non specific sign of hypocalcemia and this was also observed in our patient. A subcapsular cataract is a common sequel of hypocalcemia. In chronic hypocalcemia, calcification of the basal ganglia, cerebral cortex and cerebellum are seen in the CT scan findings  . The relationship to pre-existing epilepsy or convulsive disorders is not well understood because this calcification can be asymptomatic, incidental finding in some patients. In other cases Parkinsonism, Fahr's syndrome, choreoathetosis , or dysphonic spasms are present and may or may not be directly related to the calcification .
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