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Hypocalcaemia

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If you find Hypocalcaemia and the cause is not obvious then always look for low magnesium as it causes end-organ resistance to PTH and inhibits the hypocalcaemic feedback loop

Severe Hypocalcaemia Management Summary. Are they taking Digoxin ?
Ensure patient is on a ECG monitor and in a clinically appropriate environment If level < 1.9 mmol/L or symptom give 10-20 ml calcium gluconate 10% solution over 20 mins If severe stridor, continuing seizures, tetany refer to ITU. If symptoms continue then IV Calcium Gluconate 100 ml of 10% in 1 L N-Saline over 1-2 hours Treat until symptoms improve and calcium better. Start Oral calcium and Vitamin D Calcium can worsen Digoxin toxicity so avoid it. Treat any hypomagnesaemia Side effects of Calcium Gluconate are acute hypotension and arrhythmias, local thrombophlebitis, cardio-toxicity, hypotension, taste disturbance, nausea, flushing, vomiting and sweating

Severe Hypocalcaemia Management Summary. Are they taking Digoxin ?

Ensure patient is on a ECG monitor and in a clinically appropriate environment
If level < 1.9 mmol/L or symptom give 10-20 ml calcium gluconate 10% solution over 20 mins
If severe stridor, continuing seizures, tetany refer to ITU.
If symptoms continue then IV Calcium Gluconate 100 ml of 10% in 1 L N-Saline over 1-2 hours
Treat until symptoms improve and calcium better. Start Oral calcium and Vitamin D
Calcium can worsen Digoxin toxicity so avoid it. Treat any hypomagnesaemia
Side effects of Calcium Gluconate are acute hypotension and arrhythmias, local thrombophlebitis, cardio-toxicity, hypotension, taste disturbance, nausea, flushing, vomiting and sweating

Normal

Calcium Values < 8.5 mg/dL or < 2.15 mmol/L
Severe hypocalcaemia <7.6 mg/dL or < 1.9 mmol/L

Aetiology

Hypocalcaemia increases membrane potential so that cells are more easily depolarised
Neuromuscular excitability with muscle contraction and cardiac arrhythmias

Causes

Cause	Clinical Features	Investigations	Management
Hypoparathyroidism	Symptoms include tetany, muscle cramps, seizures, numbness, and tingling in the hands, feet, and around the mouth; Chvostek and Trousseau signs may be positive.	Low serum calcium, low PTH levels, elevated serum phosphate, normal or low 25-hydroxyvitamin D levels.	Calcium supplementation, vitamin D analogs (e.g., calcitriol), and in some cases, recombinant PTH.
Vitamin D Deficiency	Bone pain, muscle weakness, fatigue, and in severe cases, osteomalacia or rickets in children.	Low serum calcium, low 25-hydroxyvitamin D levels, elevated PTH, low phosphate levels, low serum 1,25-dihydroxyvitamin D levels.	Vitamin D supplementation (e.g., cholecalciferol or ergocalciferol), calcium supplementation if needed, and sunlight exposure.
Chronic Kidney Disease (CKD)	Symptoms may include bone pain, muscle weakness, and signs of secondary hyperparathyroidism due to impaired vitamin D activation and phosphate retention.	Low serum calcium, elevated PTH, elevated serum phosphate, low 1,25-dihydroxyvitamin D, elevated creatinine, reduced eGFR.	Phosphate binders, active vitamin D analogs (e.g., calcitriol), calcium supplementation, and management of underlying kidney disease.
Hypomagnesemia	Muscle cramps, tetany, seizures, arrhythmias, and refractory hypocalcemia, often seen in chronic alcoholism, malnutrition, or malabsorption.	Low serum magnesium, low serum calcium, low or inappropriately normal PTH, normal or low serum potassium.	Magnesium supplementation (oral or IV), correction of calcium levels, and addressing underlying causes of magnesium loss.
Acute Pancreatitis	Severe abdominal pain, nausea, vomiting, hypocalcemia due to fat saponification in the inflamed pancreas.	Low serum calcium, elevated serum lipase and amylase, imaging studies showing pancreatic inflammation, signs of systemic inflammation.	Supportive care (IV fluids, pain control), calcium supplementation in severe cases, and treatment of underlying pancreatitis.
Pseudohypoparathyroidism	Similar to hypoparathyroidism, with physical features such as short stature, round face, short hand bones, and mental retardation.	Low serum calcium, elevated PTH, low phosphate levels, genetic testing for GNAS mutations.	Calcium supplementation, vitamin D analogs, and management of associated endocrine abnormalities.
Sepsis	Systemic signs of infection, hypotension, multi-organ failure, often associated with hypocalcemia due to increased cytokine production and altered calcium metabolism.	Low serum calcium, evidence of infection (e.g., elevated white blood cell count, positive blood cultures), organ function tests.	Treatment of underlying infection with antibiotics, supportive care in ICU, calcium supplementation if severe.
Hungry Bone Syndrome	Occurs after parathyroidectomy or thyroidectomy; presents with bone pain, hypocalcemia, and hypophosphatemia due to rapid bone remineralization.	Low serum calcium, low phosphate, low magnesium, elevated alkaline phosphatase, recent history of surgery.	Aggressive calcium supplementation, vitamin D analogs, and monitoring of electrolytes postoperatively.

Clinical: Acute

Tetany, perioral paraesthesia, cramps, Carpopedal spasms
Chvostek's sign: Tap facial nerve causes contraction of the facial muscle
Trousseau's sign: Inflation of a BP cuff > systolic for 3 minutes causes carpopedal spasm
Patients can even develop laryngeal spasm and stridor.
Severe cases can result in papilloedema
Seizures: all types have been reported
ECG changes include prolonged QT interval and arrhythmias

Trousseau's sign with acute hypocalcaemia

Clinical: Chronic

Poor dentition, Seizures, neuromuscular irritability
Dry skin, coarse hair, brittle nails, psoriasis, chronic pruritus
Calcification of basal ganglia with extrapyramidal signs
Calcification of cerebellum, and cerebrum may occur
Papilloedema, Subcapsular Cataracts
Psychiatric manifestations such as depression or psychosis.

Investigations

U&E: Renal failure, Corrected calcium, Albumin, Phosphate, Mg,
iPTH: the single most important diagnostic test
Long QT can lead to arrhythmias
Vitamin D and metabolites
ECG: Prolonged QT interval, cardiac arrhythmias

Low Calcium and High PTH

Chronic kidney disease: Low Ca, High P, High ALP and PTH
Vitamin D deficiency: Low Ca, Low P, High ALP and PTH
Pseudohypoparathyroidism
Hypomagnesaemia(consider PPI associated hypomagnesaemia)
Rhabdomyolysis initially
High phosphate
Acute respiratory alkalosis (increased albumin binding, relative fall in free ionised calcium)
Acute pancreatitis (free fatty acids chelate calcium)
Drugs: cisplatin, bisphosphonates, phenytoin, bisphosphonates, rifampicin)
Citrate following large transfusion

Low Calcium Low PTH

Hypoparathyroidism: serum calcium is low, phosphate is high
Hypoparathyroidism can be congenital, autoimmune, after thyroid or parathyroid surgery
Hypomagnesaemia (consider PPI associated hypomagnesaemia)

Management

Mild hypocalcaemia level 1.9-2.13 mmol/L: Oral supplements of calcium. May also need Vitamin D or magnesium depending on the cause. Monitor serum calcium levels weekly. Once stable, monitor at 3-6 monthly intervals. Titrate Calcium according to serum calcium levels. Commence oral calcium supplements such as Sandocal 1000, 2 tablets BD (Alternatives include Adcal 3 tablets BD, Cacit 4 tablets BD, or Calcichew Forte 2 tablets BD.
Severe e.g. Tetany or Corrected calcium < 1.9 mmol/L : ABC, Manage seizures, arrhythmias, give 10ml calcium gluconate 10% solution in 100mls sodium chloride 0.9% or glucose 5% over 10-20 mins depending on urgency. It can be given neat by slow IV injection over at least 3 minutes in an emergency (e.g. Tetany)but ECG monitoring is recommended especially in those at risk of arrhythmias or with cardiac disease. Monitor serum calcium levels (2 hours after dose) and repeat calcium gluconate as required according to levels. If the patient is symptomatic an infusion is often needed to prevent a recurrence. If calcium still remains low then consider adding 100ml of calcium gluconate 10% injection into 1000ml 0.9% Saline or glucose 5% and start at 50ml/hr. Adjust rate according to the response. Monitor serum calcium levels 4 -6 hourly
Continuing hypocalcaemia can be managed acutely by administration of Oral Calcium and Vitamin D and definitive treatment of cause where possible
As calcium is highly irritant it should be administered via a small needle into a large vein to avoid extravasation. Rapid administration of calcium gluconate may result in hot flushes, hypotension, bradycardia, arrhythmias and cardiac arrest.
Great care is required when administering IV calcium to patients taking digoxin. Calcium enhances the effects of digoxin on the heart and may precipitate digitalis intoxication.
Oral calcium administration may lead to diarrhoea or constipation, nausea and gastric pain. Oral calcium impairs the absorption of a number of other medicines (including tetracyclines, iron and bisphosphonates)and an interval of at least three hours should be left between taking calcium and these medicines
Calcium chloride can be used as an alternative to calcium gluconate, but it is more irritant to veins and should only be given via a central line

References

PLEASE NOTE LEGAL ADVICE: The contents are under continuing development and improvements and may contain errors of omission or fact. Feedback vital and always welcome at drokane at gmail.com. This is not to be used for the assessment, diagnosis or management of patients. It should not be regarded as medical advice. It is only for educational purposes. Please adhere to your local protocols. If you are unwell please seek healthcare advice from your doctor. This does not replace senior or specialist advice. If you do not accept this then please do not use the website. If you need medical advice, please consult a doctor or other appropriate medical professional. If you are a medical professional and you need advice then speak to your senior or colleagues.

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