DO NOT USE FOR CLINICAL PRACTICE
Please use current guidelines available on the UHNM intranet for patient treatment
Please use current guidelines available on the UHNM intranet for patient treatment
RECOGNITION AND ASSESSMENT
- Term or preterm babies birth weight ≥1500 g: total serum calcium <2 mmol/L or ionised fraction <1.1 mmo/L
- Preterm baby, birth weight <1500 g: total serum calcium <1.75 mmol/L or ionised fraction <1 mmol/L
SYMPTOMS AND SIGNS
- Early onset occurs in first 2–3 days of life and is usually asymptomatic
- Late onset develops after first 2–3 days of life and typically occurs at the end of the first week
- Most babies are asymptomatic and identified on screening
- Characteristic sign is increased neuromuscular irritability including:
- jitteriness and irritability
- generalised/focal seizures
- non-specific symptoms e.g.:
- poor feeding
- lethargy
- apnoea
- prolonged QTc on ECG
- rare presentations:
- stridor
- bronchospasm
- pylorospasm
CAUSES
- Early onset:
- prematurity
- intrauterine growth restriction
- babies of diabetic mother
- hypoxic ischaemic encephalopathy
- hypomagnesaemia
- hypoparathyroidism
- syndromes e.g. DiGeorge syndrome
- maternal hyperparathyroidism
- Late onset:
- high phosphate load – cow’s milk, renal failure
- hypomagnesaemia
- parenteral nutrition
- exchange transfusion
- alkalosis
- maternal hypercalcemia
- maternal vitamin D deficiency
- transient hypoparathyroidism
- syndromes and genetic mutations e.g. DiGeorge and Kenny-Caffey syndromes
INVESTIGATIONS
- Serum calcium
- only monitor if risk factors, most babies with hypocalcaemia are asymptomatic
- well preterm baby with birth weight >1500 g and well term babies of diabetic mothers receiving milk feedings on day 1 of life do not need testing routinely
- ionised calcium preferred
- if using total calcium, measure albumin and correct for hypoalbuminemia
- Phosphate
- Magnesium
- Persistent hypocalcaemia or severe hypocalcaemia despite adequate calcium therapy:
- 25-hydroxyvitamin D level
- renal function tests
- liver function test
- alkaline phosphatase
- parathyroid hormone level
- urinary calcium:creatinine ratio
- ECG for prolonged QTc interval
- if pseudohyperparathyroidism suspected, X-ray hand
- chest X-ray for thymic shadow
- if hypoparathyroidism suspected, renal ultrasound
- if DiGeorge syndrome suspected, echocardiography
- genetic test for gene mutations or suspected syndrome e.g. DiGeorge syndrome
MANAGEMENT
See Flowchart: Diagnostic approach to neonatal hypocalcaemia
Asymptomatic babies
- Most babies with early onset hypocalcaemia recover with nutritional support; so early feeding provides adequate calcium
- Babies requiring IV fluid: add calcium gluconate 10% 0.46 mmol/kg/day (= 2 mL/kg/day) to IV fluid and give as continuous infusion
- baby tolerating oral feeds: give 0.25 mmol/kg oral 6-hrly
Symptomatic hypocalcaemia
- If seizures, prolonged QT interval, apnoea, unstable, hypotension or poor feeding give IV calcium gluconate 10% 0.11 mmol/kg (= 0.5 mL/kg) over 5–10 min followed by maintenance
- dilute with sodium chloride 0.9% or glucose 5% 4 mL to each 1 mL calcium gluconate 10% to give a concentration of 45 micromol/mL. Can be given undiluted via central line in an emergency
- doses up to 0.46 mmol/kg (= 2 mL/kg calcium gluconate 10%) have been used
- maximum rate of administration 22 micromol/kg/hr
- Stable baby or following acute treatment
- oral calcium dose 0.25 mmol/kg 6-hrly
- if enteral feeds not tolerated add calcium gluconate 10% 0.5 mmol/kg/day to IV fluid as above
- If symptomatic hypocalcaemia: hypomagnesaemia – magnesium sulphate 100 mg/kg IV/ deep IM 12-hrly for 2–3 doses
- Vitamin D deficiency give 1000–2000 units daily and adjust dose according to response
- Hyperphosphataemia
- high calcium, low phosphate diet
- human milk is preferable, if not available, use formula with low phosphate 60/40 and oral calcium
IV calcium precautions and considerations
- Extravasation can cause skin and subcutaneous tissue necrosis (see Extravasation guideline). Monitor IV site closely
- Continuous infusion preferred to bolus, but use bolus for initial management in symptomatic hypocalcaemia
- Bolus IV calcium can cause dysrhythmias – administer slowly over 5–10 min with cardiac monitoring
- Calcium can be given via UVC provided catheter tip is in vena cava
- inadvertent administration into portal vein can cause hepatic necrosis
- Do not mix calcium solutions with those containing phosphorus or bicarbonate as this can cause precipitation
SUBSEQUENT MANAGEMENT
- Monitor bone profile and phosphate levels according to clinical need
- If calcium normal after 48 hr treatment, halve maintenance dose
- If calcium fails to normalise investigate for underlying cause
- For extreme preterm babies with late onset hypocalcaemia [see Metabolic bone disease (MBD) guideline]
- Hyperphosphataemia – calcium and phosphate normalise in 3–5 days. Stop calcium after 1 week and switch to normal formula in 2–4 weeks