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Common electrolyte disorders in primary care

Common electrolyte disorders in primary care. Steve Hyer. ELECTROLYTES. Approach. History including drugs Examination including fluid status, blood pressure Screening tests Confirmatory tests. Thinking about electrolytes. Excess/reduced intake. Redistribution. Excess/reduced Loss.

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Common electrolyte disorders in primary care

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  1. Common electrolyte disorders in primary care Steve Hyer

  2. ELECTROLYTES

  3. Approach • History including drugs • Examination including fluid status, blood pressure • Screening tests • Confirmatory tests

  4. Thinking about electrolytes Excess/reduced intake Redistribution Excess/reduced Loss

  5. Is hyponatraemia important? 3 reasons…… • The wrong treatment can be disastrous • Rapid correction can be disastrous • Acute severe hypoNa associated with increased mortality T1: Low density T2: High density

  6. Sodium Potassium Calcium Scope

  7. Case 1 • 69y FNa 121 • Previously Na 139 • Started bendro 10d previously • Stopped bendro: Na 134 10d later. Diagnosis:Thiazide-induced hyponatraemia

  8. Case 2 • 88y M • Acutely unwell with sodium 120 mmol/l and signs of pleural effusion. • Chest CT scan showed extensive inoperable bronchial carcinoma. . Diagnosis:SIADH associated with carcinoma bronchus

  9. Case 3 • 83y F • Na 126–129 mmol/l following AP resection and ileostomy. • Urine: maximal sodium conservation. • Na normalised by reversal of ileostomy . Diagnosis:Salt and water loss through high flow stoma

  10. Case 4 • 56y M • 10d diarrhoea and vomiting. • Na 108 mmol/l K 5.5 • Subsequent investigations confirmed Addison’s disease. . Diagnosis:Hyponatraemia due to adrenal insufficiency

  11. 2 important hormones….

  12. No aldosterone! (Adrenal insufficiency) ACE-inhibitors effectively lead to low aldosterone; can cause hypoNa

  13. Diagnosis adrenal insufficiency SYNACTHEN TEST

  14. Enhanced ADH release • Tumours releasing ADH eg Ca bronchus • CNS disorders affecting hypothalamus eg SAH • Pain especially thoracic • Nausea • Opiates, SSRIs, CBZP • Atypical pneumonia V2 receptors Dilutional hyponatramia

  15. One important bit of the kidney….

  16. Distal convoluted tubule This is where the aldosterone works • Drugs • Renal tubular acidosis • Chronic pyelonephritis

  17. Excess water intake with low solutes

  18. Low solute intake: Fun runners • Drinking fluids every mile • Gain weight after run! • Drink 3 litres + in a run of 1-2 hrs • Severe hyponatraemia and even death Non elite runner

  19. Low solute intake: Beer potomania Beer • Very low sodium/ potassium • Maximum 4-5 litres of electrolye free water excretable per day • In absence of solute, >5L beer; severe hypoNa Tea + toast old ladies

  20. Primary polydipsia • Low osmotic threshold to feel thirsty • Unable to suppress thirst • Exaggerated thirst Hyponatraemia + polydipsia + polyuria

  21. Diagnosis……

  22. Clinical symptoms

  23. Step 1: Assess Volume status Mucosal membranes, tongue, skin turgor, urine output

  24. Step 2: CLASSIFY Hyper-volaemic Normo-volaemic Hypo-volaemic Weight: Down OK Up

  25. Step 3: Evaluate: Clinical

  26. Step 4: Evaluate: Laboratory Conserving sodium Losing sodium in urine

  27. Management SIADH • Underlying cause • Fluid restrict (0.5-1L/d) • May take days to come down • Maintain Na intake • (Demeclocycline-causes NDI) • VAPTANS (e.g.Tolvaptan) V2 blocker

  28. Tolvaptan • Oral agent • Currently only in secondary care for chronic SIADH • Expensive but could reduce hospital stay • Especially where fluid restriction poorly tolerated • C/I Hypovolaemic hypoNa • ?long term

  29. Secondary care Special tests • Hypertonic saline test • Water loading tests • Measurement of AVP • Hypertonic saline infusions –Na rise not >10mmol/d • Scans, etc DDI: Dipsogenic DI

  30. Summary: Hyponatramia • Multitude of causes • Many patients with chronic mild hyponatraemia have adapted and apparently very well- may decompensate in acute illness • First do no harm!

  31. History Thirst/ Polyuria No symptoms Drugs Examination Dehydrated Excessive water loss Hypernatraemia Na>145 Think diabetes insipidus

  32. Algorithm Na Loss of water Loss of water

  33. Hypokalaemia History • Diarrhoea, vomiting • No symptoms • Drugs eg Ventolin, diuretics, insulin Examination • Fluid status • Blood pressure Think diuretics

  34. Cola drink hypokalaemia • Sugar++++ • Caffeine +++ • At least 2 litres/day

  35. Hypertension + low K+ • Think Conn (Hyper-aldosteronism) • Think Cushing • Think renal artery stenosis Renin: Aldo ratio

  36. Algorithm K Gut loss Renal loss

  37. History Renal No symptoms Drugs eg ACE-I, spiro, amiloride Examination Addisons Renal Hyperkalaemia K>5.0 Think renal failure Don’t forget haemolysed samples, old samples

  38. Algorithm Output Input Don’t forget Addison

  39. Hypercalcaemia Ca>2.6 • Mild hypercalcaemia (Ca <3mmol) • Mostly due to primary hyperparathyroidism • Usually asymptomatic • Diagnosis: Ca blood/ urine + PTH

  40. Recommending PTH-ectomy • Patient fit for surgery • Significantly reduced BMD on DEXA scan • Reduced renal function (eGFR) • Ca>2.85 • History of stones • Increased Ca excretion Frail elderly: consider bisphosphonate infusion

  41. Moderate-severe Ca • Consider malignancy esp older patient • Myeloma • Sarcoidosis • Thyrotoxicosis • FHH • Drugs Bisphosphonates

  42. Malignant hypercalcaemia Tumour mets Non-metastatic (PTH-RP)

  43. Algorithm

  44. Low calcium Ca <2.2mmol • Usually Vitamin D deficiency (30% elderly, 90% Asians?) • May be Chronic renal failure • HypoPTH • PseudohypoPTH • (Low Mg) Lack of sun Phytate in chipatis Housebound

  45. High Ca High PTH Low Ca High PTH High Ca Low PTH Low Ca Low PTH

  46. Assessment Ca History • Diet/ diarrhoea/ mal-absorption • Thyroid surgery • Drugs eg phenytoin Examination • Tetany, Chvostek • Renal Investigations • Ca/P/ Alk P’ase/ Vit D/ PTH

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