Related Subjects:
|Calcium Physiology
|Calcitonin
|Hypocalcaemia
|Hypercalcaemia
|Hypomagnesaemia
|Hypermagnesaemia
|Primary Hyperparathyroidism
|Familial hypocalciuric hypercalcaemia (FHH)
|Sarcoidosis
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 ? |
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- Ensure patient is on a cardiac monitor and in a clinically appropriate environment
- If level < 1.9 mmol/L or symptom give 10-20 ml calcium gluconate 10% solution in 100 mls slowly over 20 mins
- If severe stridor, continuing seizures, tetany refer to ITU.
- Theoretical risk giving Calcium to those with Digoxin toxicity
as they are at risk of arrest with rapid correction
- Side effects of IV Calcium are local thrombophlebitis, cardio-toxicity, hypotension, taste disturbance, nausea, flushing, vomiting and sweating
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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
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