An 8-year-old girl is brought with complaints of short stature and recurrent seizures. She was started on antiepileptics about 6 months back but 2 days back she developed tetany and her serum calcium was found to be 5 mg/dL and is hence referred to endocrinology. Her calcium levels at the time of seizures were not checked in the past. She is conscious and oriented at the time of examination. Her pulse rate is 110/min and BP is 90/60 mm Hg and respiratory rate is 20/min; she is afebrile. She has moon facies and alopecia. Her BMI is normal, and secondary sexual characteristics are well-developed. There are no bony deformities in the limbs. Signs of latent tetany (Chvostek and Trousseau signs) are positive. There are bilateral cataracts but no evidence of papilledema. Examination of other systems namely cardiovascular, respiratory, and nervous is normal. Emergency investigations show low total serum calcium of 5 mg/dL (8.5–10.5 mg/dL) and her ionized calcium is 2.5 mg/dL (4.60–5.30 mg/dL). Serum magnesium level (1.5 mg/dL) is low normal and her phosphorus is 8 mg/dL (2.5–4.90 mg/dL) and her parathormone is 500 pg/mL (range 11 to 79.5 pg/mL). A noncontrast (NCCT) scan of the brain reveals bilateral basal ganglia and pineal gland calcification. The QTc interval is prolonged to 0.46 seconds. A provisional diagnosis of hypocalcemic seizures is made.
How is calcium replacement done in emergency in patient with hypocalcemia?
Medicine
Patients with acute symptomatic hypocalcemia (serum calcium usually below 7.0 mg/dL, and ionized calcium usually below 3.2 mg/dL) should be treated promptly with IV calcium. Calcium gluconate is preferred option over calcium chloride because it causes less tissue necrosis, if extravasated. The first 100–200 mg of elemental calcium (1–2 ampoules of 10% calcium gluconate [93 mg/10 mL ampoule]) should be given over 10–20 minutes. Calcium for infusion should be diluted in 50–100 mL of saline or 5% dextrose solution to avoid vein irritation. Faster administration may result in cardiac dysfunction, even arrest. This should be followed by slow calcium infusion at 0.5–2 mg/kg/hr which can be done by adding 10 ampoules of calcium gluconate in 500 mL of 5% dextrose.
Calcium infusion should be continued until the patient is receiving effective doses of oral calcium (1–3 g of elemental calcium daily) and vitamin D and is maintaining normal calcium levels. The infusion solution should not contain bicarbonate or phosphate because these can form insoluble calcium salts. If bicarbonate or phosphate administration is necessary, a separate IV line should be used. Serum calcium should be measured every 4–6 hours to maintain serum calcium levels at 8–9 mg/dL. Patients with cardiac arrhythmias or patients on digoxin therapy need continuous ECG monitoring during calcium replacement because calcium potentiates digitalis toxicity. Coexisting hypomagnesemia (serum Mg levels <1.8 mg/dL) should be considered in every patient, and if present or if the magnesium status is unknown, magnesium should be supplemented. Great care should be taken in patients with impaired renal function because they cannot excrete excess magnesium. Magnesium is given in an infusion and initiated with 2 g magnesium sulfate over 10–15 minutes followed by 1 g/hr.
The cause of hypocalcemia in this patient is pseudohypoparathyroidism. The above mentioned patient is started on calcium infusion and also started on oral calcium supplementation and active vitamin D. She recovers with treatment and is continued on calcium and active vitamin D.
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