Management Of Hyponatraemia - remedy.bnssgccg.nhs.uk€¦ · Chronic hyponatraemia Should be...

Version 1 June 2014 Review June 2017 Author(s) Jessica Triay Consultant Acute Medicine, Rachel Bradley Consultant in Elderly Care, Natasha Thorogood Consultant in Endocrinology

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SETTING Medical division

FOR STAFF Doctors

PATIENTS Adults only

CLINICAL GUIDELINE

Page 1 Definition of hyponatraemia. Apparent Hyponatraemia. Page 2 Management of chronic or mild-moderately symptomatic hyponatraemia. Page 3 Immediate management: severely symptomatic hyponatraemia Page 4 Diagnosis of SIADH (Syndrome of Inappropriate Anti Diuretic Hormone). Drugs that cause hyponatraemia.

DEFINITION The management of hyponatraemia in the majority of cases is dictated by symptoms rather than degree of biochemical disturbance. (Venous blood gas provide an accurate evaluation of sodium status.) Moderately Symptomatic Nausea (without vomiting), confusion, headache. Sodium usually >125 mmol/L Severely Symptomatic Vomiting, seizures, drowsiness or coma (GCS < 8). Sodium usually <125 mmol/L Chronic hyponatraemia Should be assumed if rate of sodium fall is uncertain.

Slow correction is essential (10mmol over 24 hours) to avoid osmotic demyelination.

Acute hyponatraemia Rare; Evolves in less than 48 hours, usually due to water loading Brainstem herniation may occur with sodium <120mmol/L.

APPARENT HYPONATRAEMIA:

TARGET SODIUM INCREASE:

5 mmol/L over 24 hours is acceptable

No more than 10-12 mmol/L over first 24 hours (depending on risk of osmotic demyelination)

No more than 8 mmol/L over any subsequent 24 hour period RE-EVALUATION:

According to clinical symptoms and management.

Treatment with hypertonic saline (2.7%): Evaluate and repeat serum sodium at 2, 6, 12 and 24 hours

Treatment with hypertonic saline (0.9%): Evaluate and repeat serum sodium at 4, 12 and 24 hours

Treatment with fluid restriction only: Evaluate and repeat serum sodium at 12 and 24 hours

More frequent monitoring may be required in certain cases (e.g. high risk, rapidly changing serum sodium)

Continue to monitor serum sodium at least once daily until back to baseline or normal range

Cause Investigations

Hyperglycaemia Does sodium correct to normal range? A rule of thumb is: Serum sodium + [(glucose – 10) / 3] Severe lipaemia or severe hyperproteinaemia Osmolar gap is greater than 10 Osmolar gap = Serum osmolality – calculated osmolality Calculated osmolality = (2 x Na) + urea + glucose Presence of osmolytes Infusions of glucose, mannitol, hyperosmolar contrast media. Presence of high alcohol, ethylene glycol or lactate

Serum glucose, urea and electrolytes NB Blood gas samples give accurate sodium despite hyperglycaemia Laboratory automatically flag lipaemic samples Serum osmolality, Total protein Consider: Lactate, Ethylene glycol (discuss with laboratory)

Clinical Guideline: MANAGEMENT OF HYPONATRAEMIA


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EVALUATE PATIENT

Discuss with senior doctor/Consultant Send investigations but do not delay treatment

• Give 100mls 2.7% Saline • Intravenous via large vein over 30 minutes

• Use infusion pump

Commence 2.7% saline infusion using Androgue formula. Beware this often overestimates sodium replacement. Aim: 1 mmol/L per hour increase in sodium. Check sodium at least 2 to 4 hourly whilst on infusion. Stop infusion once any of the following occur:

• symptoms improve, or • sodium increases by 10 mmol/L in total,

or • sodium reaches 130 mmol/L.

If symptoms do not respond consider alternative

diagnosis.

2) Have symptoms resolved?

Repeat VBG after 20 minutes & evaluate patient: 1) Is Sodium increase >5 mmol/L in total?

Is systolic BP >90 mmHg? If not: treat for hypovolaemia with 0.9% saline (rate according to requirement)

Aim systolic blood pressure >90mmHg & euvolaemia (clinically or CVP >10 cm H2O)

Repeat sodium 2 hourly during resuscitation phase

Higher risk of osmotic demyelination:

• Alcoholism • Diabetes mellitus

• Malnutrition

• Elderly • Psychiatric polydipsia

• Post-operative

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Guidance for Potassium replacement: Correction of hypokalaemia can increase rate of sodium rise. If K < 2.0 mmol/L or unsafe swallow, 1 litre 10% Dextrose + 40mmol KCL over 8 hours If K 2.0 to 2.5 mmol/L give two Sando K three times daily orally/via NG If K >2.5 then do not replace until after 24 hours (due to unpredictable rise in sodium)

Guidance if sodium rises above target: • Discontinue any active treatment • Seek senior advice. All patients who require sodium re-lowering should be in a high care environment.

Consider either: 5% glucose 10mls/kg lean body weight over 1 hour (should reduce sodium by 2mmol/L). Repeat as indicated. Strict monitoring of fluid balance and urine output. Or Desmopressin 2 mircrograms subcutaneously. Can be repeated 8 hourly.

• Repeat serum sodium after 1, 6 and 12 hours.

Evaluate patient: Severe Symptoms (Confusion, anorexia, nausea, muscle weakness, drowsiness, coma, seizures)

(and sodium increase following rehydration <5 mmol/L)

Consider high care environment (discussions should involve medical consultant)

Await investigations

Treat according to cause (Page 2)

yes

Immediate Management: Severe Symptomatic Hyponatraemia

Androgue formula

http://www.medcalc.com/sodium.html (note: mEq/ml = mmol/L)

RE-EVALUATION:

According to clinical symptoms and management.

Hypertonic saline (2.7%): Evaluate & repeat sodium at 2, 6, 12 & 24 hours

Hypertonic saline (0.9%): Evaluate & repeat sodium at 4, 12 & 24 hours

More frequent monitoring may be required in certain cases (e.g. high risk, rapidly changing serum sodium)

Monitor sodium at least once daily until back to baseline or normal range



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Drugs that can cause hyponatraemia

Diuretics Thiazides, Renin/Angiotensin system agents, Amiloride, Loop diuretics

Antidepressants Tricyclics, Selective Serotonin Reuptake Inhibitors, Monoamine Oxidase Inhibitors

Antiepileptics Carbamazepine, Duloxetine, Gabapentin, Lamotrigine

Proton pump inhibitors Omeprazole, Lansoprazole

Heparin Including Low Molecular Weight Heparins

Analgesia Non-Steroidal Anti-Inflammatories (NSAIDS), Opiates

Other Anaesthetic agents, Anticancer drugs, Terlipressin, MDMA

DIAGNOSIS OF SIADH (Syndrome of Inappropriate Antidiuretic Hormone) Essential diagnostic criteria

Decreased serum osmolality (<275 mOsm/kg)

Urinary osmolality >100 mOsm/kg during hypo-osmolality

Clinical euvolaemia (exclude obvious hypovolaemia)

Urinary sodium >30 mmol/L with normal dietary sodium intake (although is often >60 mmol/L)

Normal thyroid and adrenal function

No diuretic agents the week prior to evaluation Supporting diagnostic criteria for SIADH. Consider these investigations in selected cases where diagnosis remains unclear following senior review.

Serum urate <0.24 mmol/L

Serum urea <3.6 mmol/L

Failure to improve or worsening of hyponatraemia after 0.9% saline infusion

Improvement of hyponatraemia with fluid restriction In patients receiving diuretics, a fractional urate excretion can be measured. Excretion over 12% appears to be optimal to confirm the diagnosis of SIADH and <8% excludes SIADH. Fractional uric acid excretion is calculated as:

Fractional urate excretion (%)

= [Urine urate (mmol/L)/serum urate (µmol/L)] x [serum creatinine(µmol/L)/urine creatinine (mmol/L)] x 100

Causes of SIADH: If SIADH is diagnosed, an underlying cause should be sought.

Consider

Cancer Carcinomas: e.g. Lung, oropharynx, gastrointestinal, genitourinary Lymphomas, leukaemia Sarcomas

CT head, chest, abdomen & pelvis Endoscopy (if anaemia) LDH level

Pulmonary diseases

Any infections Asthma Cystic fibrosis Respiratory failure associated with positive pressure breathing

CT chest

Central nervous system

Infections: e.g. meningitis, encephalitis Stoke, bleeding and masses Other: e.g. multiple sclerosis, Guillain-Barre, head injury

CT head Lumbar puncture

Infections HIV/AIDS HIV test if high risk

References: 2007 Verbalis JG et al. The American Journal of Medicine Vol 120 (11A), S1–S21 Expert Panel Recommendations 2010 Eur J Endocrinol June 1, 162, S1-S3. (Covering multiple aspects of hyponatraemia management) 2014 Eur J Endocrinol 170:3 G1-G47Clinical Practice Guideline on diagnosis and treatment of hyponatraemia.

Commented on by Dr Keiron Rooney (ITU) and Dr Andrew Day Consultant Medical Biochemist. Guideline ratified by the Department of Endocrinology May 2014.

RELATED DOCUMENTS

“Sick day rules” for adult endocrine patients with proven glucocorticoid deficiency/dependency http://nww.avon.nhs.uk/dms/download.aspx?did=15388

SAFETY Hyponatraemia is associated with increased morbidity, mortality and length of hospital admission.

QUERIES Contact: Dr Natasha Thorogood (Consultant Endocrinologist) or Dr Rachel Bradley, (Consultant Elderly Care Medicine) Medical Registrar on call bleep 2997 Endocrine Registrar Bleep 6216. Available Monday-Friday 9am-5pm Endocrine Consultants available through switchboard Monday-Friday 9am-5pm

http://nww.avon.nhs.uk/dms/download.aspx?did=15388

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Management Of Hyponatraemia - remedy.bnssgccg.nhs.uk€¦ · Chronic hyponatraemia Should be...

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