Common electrolyte disorders Common electrolyte disorders in primary carein primary care

Steve HyerSteve Hyer

ELECTROLYTESELECTROLYTES

ApproachApproachHistoryHistory including including drugsdrugs

Examination Examination including fluid including fluid status, blood status, blood pressurepressure

Screening testsScreening tests

ConfirmatoryConfirmatory teststests

Thinking about electrolytesThinking about electrolytes

Excess/reduced intake

Excess/reduced Loss

Redistribution

Is hyponatraemia important?Is hyponatraemia important?3 reasons……3 reasons……1.1. The wrong The wrong

treatment can be treatment can be disastrousdisastrous

2.2. Rapid correction Rapid correction can be disastrouscan be disastrous

3.3. Acute severe Acute severe hypoNa hypoNa associated with associated with increased increased mortalitymortality

T1: Low density T2: High density

ScopeScope

SodiumSodium

PotassiumPotassium

CalciumCalcium

Case 1Case 169y F69y F Na 121Na 121

Previously Na 139Previously Na 139

Started bendro 10d Started bendro 10d previouslypreviously

Stopped bendro: Stopped bendro: Na 134 10d later.Na 134 10d later.

Diagnosis: Thiazide-induced hyponatraemia

Case 2Case 288y M88y MAcutely unwell with Acutely unwell with sodium 120 mmol/l sodium 120 mmol/l and signs of pleural and signs of pleural effusion. effusion. Chest CT scan showed Chest CT scan showed extensive inoperable extensive inoperable bronchial carcinoma. .bronchial carcinoma. .

Diagnosis: SIADH associated with carcinoma bronchus

Case 3Case 383y F 83y F Na 126–129 mmol/l Na 126–129 mmol/l following AP resection following AP resection and ileostomy. and ileostomy. Urine: maximal Urine: maximal sodium conservation.sodium conservation.Na normalised by Na normalised by reversal of ileostomy .reversal of ileostomy .

Diagnosis: Salt and water loss through high flow stoma

Case 4Case 456y M 56y M 10d diarrhoea and 10d diarrhoea and vomiting. vomiting. Na 108 mmol/l K 5.5 Na 108 mmol/l K 5.5 Subsequent Subsequent investigations investigations confirmed Addison’s confirmed Addison’s disease. .disease. .

Diagnosis: Hyponatraemia due to adrenal insufficiency

2 important hormones….2 important hormones….

No aldosterone! No aldosterone! (Adrenal insufficiency)(Adrenal insufficiency)

ACE-inhibitors effectively lead to low aldosterone; can cause hypoNa

Diagnosis adrenal insufficiencyDiagnosis adrenal insufficiency

SYNACTHEN TEST

Enhanced ADH releaseEnhanced ADH releaseTumours releasing Tumours releasing ADH eg Ca bronchusADH eg Ca bronchus

CNS disorders CNS disorders affecting affecting hypothalamus eg SAHhypothalamus eg SAH

Pain especially Pain especially thoracicthoracic

NauseaNausea

Opiates, SSRIs, CBZPOpiates, SSRIs, CBZP

Atypical pneumoniaAtypical pneumonia

V2 receptorsDilutional hyponatramia

One important bit of the kidney….One important bit of the kidney….

Distal convoluted tubuleDistal convoluted tubuleThis is where the This is where the aldosterone aldosterone worksworks

DrugsDrugs

Renal tubular Renal tubular acidosisacidosis

Chronic Chronic pyelonephritispyelonephritis

Excess water intake with low solutesExcess water intake with low solutes

Low solute intake: Fun runnersLow solute intake: Fun runnersDrinking fluids Drinking fluids every mile every mile

Gain weight after Gain weight after run!run!

Drink 3 litres + in a Drink 3 litres + in a run of 1-2 hrsrun of 1-2 hrs

Severe Severe hyponatraemia hyponatraemia and even deathand even death Non

elite runner

Low solute intake: Beer potomaniaLow solute intake: Beer potomaniaBeerBeer

Very low sodium/ Very low sodium/ potassiumpotassiumMaximum 4-5 litres Maximum 4-5 litres of electrolye free of electrolye free water excretable water excretable per dayper dayIn absence of In absence of solute, >5L beer; solute, >5L beer; severe hypoNasevere hypoNa Tea + toast

old ladies

Primary polydipsiaPrimary polydipsiaLow osmotic Low osmotic threshold to feel threshold to feel thirstythirstyUnable to suppress Unable to suppress thirstthirstExaggerated thirstExaggerated thirst

Hyponatraemia + Hyponatraemia + polydipsia + polydipsia + polyuriapolyuria

Diagnosis……Diagnosis……

Clinical symptomsClinical symptomsPlasma Na+Plasma Na+ SymptomsSymptoms MortalitMortalit

y (%)y (%)>125>125 Usually none. Usually none.

Occasional headache, Occasional headache, nauseanausea

Not Not reportedreported

120 -125120 -125 Headache, nausea, Headache, nausea, cramps, confusioncramps, confusion

2323

115-120115-120 Agitation, drowsy, Agitation, drowsy, stuporstupor

3030

<115<115 Seizures, comaSeizures, coma 4040

Step 1: Assess Volume statusStep 1: Assess Volume status

Mucosal membranes, Mucosal membranes, tongue, skin turgor, urine tongue, skin turgor, urine outputoutput

Step 2: CLASSIFYStep 2: CLASSIFY

HyperHyper-volaemic-volaemic

NormoNormo-volaemic-volaemic

HypoHypo-volaemic-volaemic

Weight: Down OK Up

Step 3: Step 3: Evaluate: Evaluate: ClinicalClinical

Step 4: Step 4: Evaluate: Evaluate:

LaboratoryLaboratory

Conserving sodiumLosing

sodium in urine

Management SIADH Management SIADH Underlying causeUnderlying causeFluid restrict (0.5-Fluid restrict (0.5-1L/d)1L/d)May take days to May take days to come downcome downMaintain Na intakeMaintain Na intake(Demeclocycline-(Demeclocycline-causes NDI)causes NDI)

VAPTANS VAPTANS (Conivaptan in US)(Conivaptan in US)

V2 blocker

Secondary careSecondary care Special testsSpecial tests

Hypertonic saline Hypertonic saline testtestWater loading testsWater loading testsMeasurement of Measurement of AVPAVPHypertonic saline Hypertonic saline infusions –Na rise infusions –Na rise not >10mmol/dnot >10mmol/dScans, etcScans, etc

DDI: Dipsogenic DI

Summary: HyponatramiaSummary: Hyponatramia

Multitude of causesMultitude of causes

Many patients with chronic mild Many patients with chronic mild hyponatraemia have adapted and hyponatraemia have adapted and apparently very well- may apparently very well- may decompensate in acute illnessdecompensate in acute illness

First do no harm!First do no harm!

Hypernatraemia Na>145Hypernatraemia Na>145HistoryHistory

Thirst/ PolyuriaThirst/ Polyuria

No symptomsNo symptoms

DrugsDrugs

ExaminationExamination

DehydratedDehydrated

Think diabetes insipidus

ExcessivExcessive water e water

lossloss

Algorithm NaAlgorithm Na

Loss of water

Loss of water

HypokalaemiaHypokalaemiaHistoryHistory

Diarrhoea, vomitingDiarrhoea, vomiting

No symptomsNo symptoms

Drugs eg Ventolin, Drugs eg Ventolin, diuretics, insulindiuretics, insulin

ExaminationExamination

Fluid statusFluid status

Blood pressureBlood pressure

Think diuretics

Cola drink hypokalaemiaCola drink hypokalaemiaSugar++++Sugar++++

Caffeine +++Caffeine +++

At least 2 litres/dayAt least 2 litres/day

Hypertension + low KHypertension + low K++

Think ConnThink Conn

(Hyper-(Hyper-aldosteronism)aldosteronism)

Think CushingThink Cushing

Think renal artery Think renal artery stenosisstenosis

Renin: Aldo ratio

Algorithm KAlgorithm K

Gut loss

Renal loss

Hyperkalaemia K>5.0Hyperkalaemia K>5.0

HistoryHistoryRenal Renal No symptomsNo symptomsDrugs eg ACE-I, Drugs eg ACE-I, spiro, amiloridespiro, amiloride

ExaminationExaminationAddisons Addisons RenalRenal

Think renal failure Don’t forget haemolysed samples, old samples

AlgorithmAlgorithm

Input Output

Don’t forget Addison

Hypercalcaemia Ca>2.6Hypercalcaemia Ca>2.6Mild Mild hypercalcaemiahypercalcaemia (Ca <3mmol)(Ca <3mmol)Mostly due to Mostly due to primary primary hyperparathyroidishyperparathyroidismmUsually Usually asymptomaticasymptomaticDiagnosis: Ca Diagnosis: Ca blood/ urine + PTH blood/ urine + PTH

Recommending PTH-ectomyRecommending PTH-ectomy Patient fit for surgeryPatient fit for surgery Significantly reduced Significantly reduced

BMD on DEXA scanBMD on DEXA scan Reduced renal Reduced renal

function (eGFR)function (eGFR) Ca>2.85Ca>2.85 History of stonesHistory of stones Increased Ca Increased Ca

excretionexcretion Frail elderly: consider bisphosphonate infusion

Moderate-severe CaModerate-severe CaConsider Consider malignancy esp malignancy esp older patientolder patient

MyelomaMyeloma

SarcoidosisSarcoidosis

ThyrotoxicosisThyrotoxicosis

FHHFHH

DrugsDrugs

Bisphosphonates

Malignant hypercalcaemiaMalignant hypercalcaemia

Tumour mets Non-metastatic (PTH-RP)

AlgorithmAlgorithm

Low calcium Ca <2.2mmolLow calcium Ca <2.2mmol

Usually Vitamin D Usually Vitamin D deficiency (30% deficiency (30% elderly, 90% elderly, 90% Asians?)Asians?)May be Chronic May be Chronic renal failurerenal failureHypoPTH HypoPTH PseudohypoPTHPseudohypoPTH(Low Mg)(Low Mg)

Lack of sun

Phytate in chipatis

Housebound

High Ca High PTH

High Ca Low PTH

Low Ca High PTH

Low Ca Low PTH

Assessment Ca Assessment Ca

HistoryHistoryDiet/ diarrhoea/ Diet/ diarrhoea/ mal-absorption mal-absorption Thyroid surgeryThyroid surgeryDrugs eg phenytoinDrugs eg phenytoin

ExaminationExaminationTetany, ChvostekTetany, ChvostekRenalRenal

InvestigationsInvestigationsCa/P/ Alk P’ase/ Ca/P/ Alk P’ase/ Vit D/ PTHVit D/ PTH

Treatment Vit D deficiencyTreatment Vit D deficiency

Calciferol (D2)Calciferol (D2)Ex: Calcium & Vit D Ex: Calcium & Vit D 400u bd400u bd

Colecalciferol (D3)Colecalciferol (D3)Ex: Adcal-D3 (400) bdEx: Adcal-D3 (400) bd

ErgocalciferolErgocalciferol10,000 u (mal-10,000 u (mal-absorption)absorption)

AnaloguesAnaloguesEx: One –Alpha Ex: One –Alpha 0.25mcg (renal 0.25mcg (renal failure)failure)