This is intended as a general guide for adults requiring emergency treatment and should not be used in isolation. More specific guidelines are available on the intranet please refer to these for a more in-depth guidance on electrolyte management. This guidance is not intended for the following settings:

• Nutrition Policy (re-feeding syndrome)
• Neonatal fluid and electrolyte management
• Electrolyte management in the ITU setting

For complicated cases or patients not responding to initial therapy contact the endocrinology team, pharmacist or clinical biochemist for advice:

Endocrine Consultant: Phone 3726
Clinical Biochemist: Ext 4395
Clinical Pharmacy: 4721/4722

High sodium – Na+ (reference range 135-145 mmol/L)

Causes:

Excess fluid loss; burns, vomiting, diarrhoea, sweating, diabetes insipidus, osmotic diuresis, primary hyperaldosteronism.

Dehydration and iatrogenic use of saline.

Sodium excess can be caused by renal failure or drug therapy e.g. Lithium, demeclocycline, NaCl/ hypertonic sodium bicarbonate.

Symptoms:

Treatment:

TBW deficit =
Current TBW x (serum Na+/140 – 1).

This formula gives estimated volume of fluid required to correct Na+ to 140 mmol/L

Current TBW: (young = 18-60, elderly= >60 years)

• Young men =60% lean body weight
• Young women=50% lean body weight
• Elderly men= 50% lean body weight
• Elderly women= 45% lean body weight

Rate of correction depends on duration of hypernatraemia:

• For acutely acquired hypernatraemia (<24hrs) treat over 24 hours
• For chronic hypernatraemia (>48hrs) correct more slowly over 1-3 days.

Correct at a rate of <0.7 mmol/L/hr
Over rapid correction can lead to central pontine myelinolysis (CPM).

TBW deficit may exceed 5L and should be corrected over 2-3 days.

Rehydrate with 5% glucose slowly, avoid rapid correction.

Desmopressin may be required in diabetes insipidus-contact Endocrinology. Check serum Na+ levels 12 hourly for mild hypernatraemia and 4 hourly if severe.

Monitor neurological status, fluid balance and for hyperglycaemia.

Low sodium – Na+ (reference range 135-145 mmol/L)

Causes:

1. Clinical assessment; Assess volume status; dehydration, oedema, JVP, lying-standing BP.
2. Determine if acute (developed within 48 hrs.) or chronic hyponatraemia
3. Check for gastroenteritis, renal failure, heart failure, liver disease, myeloma, cancer, hypothyroidism.
4. Check drugs; diuretics, proton pump inhibitors (PPIs), selective serotonin receptor inhibitors (SSRIs), neuroleptics.
5. Measure plasma osmolality and urine osmolality and urinary sodium to establish renal losses (note this will be difficult to interpret if on diuretics).
6. Treatment will be largely based on whether symptomatic or not, their volume status and the rate of onset.

Symptoms:

Treatment:

Mg2+ levels often follow same trend as Ca2+ & K+

Causes:

Acute kidney injury, haemodialysis with hard water.

Symptoms:

Absent patella reflex is first sign of toxicity, followed by nausea and vomiting, muscle weakness, impaired consciousness, neuromuscular transmission and cardiac conduction.

Treatment:

Calcium gluconate injection can be used to treat Mg2+ toxicity if not hypercalcaemic.

Ref: EKHUT pocket electrolyte guide 2nd Ed.

Mg2+ levels follow same trend as those of Ca2+ and K+

Causes:

Symptoms:

Treatment:

If a hypomagnesaemic patient is on parenteral nutrition, and has other electrolyte abnormalities and it is a symptom of refeeding syndrome contact the Nutrition team, dietician (bleep 616/419) or gastroenterology team (bleep 272/161) for advice before giving supplements.

First choice- Magnesium glycerophosphate 4 mmol tablets: 2 tablets three times a day for 3 days.

Dose limiting side effect-diarrhoea (give with or after food)

Indicated in severe low Mg2+, symptomatic or if there is low Ca2+.

Each 1gram of magnesium sulfate contains 4mmol Mg2+ .

Give 20mmol of magnesium sulfate in 250ml of 0.9% NaCl and infuse over at least 2 and half hours.

For reference: magnesium sulfate 50% w/v solution contains 2mmol/ml. It must always be diluted before use.

Contra-indicated in AV block and severe bradycardia, caution in renal failure (halve the dose due to reduced urinary excretion).

If symptoms severe e.g. serious arrhythmias (especially if hypokalaemia), give 8 mmol (2g) over 10-15 mins. Repeat if necessary, with continuous ECG monitoring. Monitor serum Mg²⁺ levels daily.

Ref: EKHUFT electrolyte guideline & FPH electrolyte guidelines for adult medical ward (not yet published).

Adjusted Calcium = serum calcium + 0.02 (40-serum albumin)

Causes:

Drugs e.g. Calcium resonium, thiazides, oestrogens, androgens, tamoxifen, lithium, supplements-calcium, vitamin D, vitamin A.

Symptoms:

If symptomatic or a corrected serum Ca >3.5mmol/L, urgent treatment is required.

Treatment:

2. Recheck serum calcium & if still >3.0mmol/L give Pamidronate.
   NB. Check renal function and PTH before initiating pamidronate.

Sodium pamidronate 60mg in 500ml 0.9% NaCl over 4 hours

• 30mg if eGFR <30ml/min
• 90mg if hypercalcaemia due to metastatic myeloma or breast cancer

Caution in renal impairment: max rate 20mg/hr.

Serum levels begin to fall within 48 hrs and usually reach their lowest level at 5 days, so re-check levels again.

Other treatments include prednisolone (40mg od) or calcitonin-but must discuss with a consultant prior to initiating.

Ref: EKHUFT pocket electrolyte guide 2nd Ed. The BNF. NICE clinical pathway guidelines on hypercalcamia. FPH intranet guidelines.

Corrected calcium = serum calcium +0.02 (40-serum albumin)

Causes:

Increased serum phosphate complexes with serum Ca++ leading to reduced Ca++.

Symptoms:

Treatment:

Sandocal 1000 (25mmol/tab) 2-3 tablets BD or Adcal D3 2 tablets BD. Best between meals: chelates with dietary phosphates. If post-thyroidectomy and hypocalcaemia persists >72 hrs start alfacalcidol 250 nanograms/day PO.

Give 1) Calcium Gluconate 10% - Give 10-20ml in 50ml 5% Dextrose until asymptomatic. Repeat as needed.

Then 2) Calcium Gluconate 10% - IV infusion of 100ml diluted in 1L 5% dextrose or 0.9% NaCl at 50-100ml/hour until calcium returns to normal.

Titrate infusion to achieve normocalcaemia and continue until treatment of underlying cause has taken effect.

Need to monitor potassium and magnesium. Treat vit D deficiency.

Continuous ECG monitoring for those with calcium<1.9 mmol/L, arrhythmias or digoxin therapy. Treat underlying cause of hypocalcaemia.

Weekly calcium levels until stable.

If on dialysis or end stage renal failure avoid large infusions-seek renal advice.

Ref: Emergency endocrine guidance: Acute management of hypocalcaemia. Society for Endocrinology UK. FPH guidelines on hypocalcaemia

Refer to the Acute Hyperkalaemia in Adults guideline: https://guidelines.fhft.nhs.uk/Renal-Acute_Hyperkalaemia_in_Adults

Causes:

Vomiting, diarrhea, severe burns, ileostomy, fistulae, low Mg++.

Increased aldosterone production e.g. liver or heart failure, Cushing’s syndrome/ disease.

Symptoms:

• Look for ECG changes (U waves, T wave flattening, ST segment changes)

Treatment:

Oral

Check Mg++ levels and replace.

Intravenous

0.9% NaCl preferred to 5% glucose

Use ready-made bags and administer via a pump.

Rate:

• 10 mmol/hr. without ECG monitoring
• 20 mmol/hr. with ECG monitoring
• 40 mmol/hr. emergencies with ECG monitoring

Maximum concentration peripherally 40mmol/L over 4 hours.
Higher concentrations must be given centrally.

References: EKHUFT pocket electrolyte guide 2nd Ed. FPH guideline for replacement of electrolytes on adult medical wards 2015 (unpublished)

Reference range 0.80-1.50 mmol/L.

Causes:

Symptoms:

Treatment:

Ref: EKHUT pocket electrolyte guide 2nd Ed.

Causes:

Vitamin D deficiency, chronic diarrhoea, hyperparathyroidism, metabolic acidosis or respiratory alkalosis, renal transplant, re-feeding syndrome, alcohol withdrawal, insulin therapy.

Diurnal variation in plasma levels: lower in the morning.

Symptoms:

Treatment:

Oral

Phosphate Sandoz 2 tablets BD for 3 days with plenty of water. (diarrhoea is a dose limiting effect.)
Each tablet: 16.1 mmol phosphate, 20.4 mmol Na, 3.1 mmol K+

Intravenous

Phosphate Polyfusor® is a 500mL polyethylene cylindrical container containing: 50mmol phosphate, 81mmol sodium and 9.5mmol potassium.

Phosphate Polyfusor® intravenous infusion: for mild-moderate (level between 0.3-0.64), or if oral route not suitable give 1-2 ml/Kg for 6-12 hours.

Maximum dose = 500ml Polyfusor® per infusion, maximum infusion rate = 150ml Polyfusor® per hour. Do not infuse with other medications; in case of renal impairment infuse over 12 hours.

Correct any hypomagnesaemia and hypocalcaemia before starting intravenous phosphate. Do not mix with other IV fluids.

Phosphate Polyfusor® intravenous infusion: for Severe hypophosphataemia (<0.32) give 2-5 ml/Kg over 6-12 hours.

Check phosphate levels daily.

Ref: FPH guidelines for replacement of electrolytes on adult medical wards (not published yet)

Adjusted calcium = serum calcium + 0.02 (40-serum albumin)