Title: Common electrolyte disorders in primary care
1Common electrolyte disorders in primary care
2 3Approach
- History including drugs
- Examination including fluid status, blood
pressure - Screening tests
- Confirmatory tests
4Thinking about electrolytes
Excess/reduced intake
Redistribution
Excess/reduced Loss
5Is 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
6Scope
7Case 1
- 69y F Na 121
- Previously Na 139
- Started bendro 10d previously
- Stopped bendro Na 134 10d later.
Diagnosis Thiazide-induced hyponatraemia
8Case 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
9Case 3
- 83y F
- Na 126129 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
10Case 4
- 56y M
- 10d diarrhoea and vomiting.
- Na 108 mmol/l K 5.5
- Subsequent investigations confirmed Addisons
disease. .
Diagnosis Hyponatraemia due to adrenal
insufficiency
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14No aldosterone! (Adrenal
insufficiency)
ACE-inhibitors effectively lead to low
aldosterone can cause hypoNa
15Diagnosis adrenal insufficiency
SYNACTHEN TEST
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17Enhanced 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
18- One important bit of the kidney.
19Distal convoluted tubule
- This is where the aldosterone works
- Drugs
- Renal tubular acidosis
- Chronic pyelonephritis
20- Excess water intake with low solutes
21Low 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
22Low solute intake Beer potomania
- Beer
- Very low sodium/ potassium
- Maximum 4-5 litres of electrolye free water
excretable per day - In absence of solute, gt5L beer severe hypoNa
Tea toast old ladies
23Primary polydipsia
- Low osmotic threshold to feel thirsty
- Unable to suppress thirst
- Exaggerated thirst
- Hyponatraemia polydipsia polyuria
24 25Clinical symptoms
Plasma Na Symptoms Mortality ()
gt125 Usually none. Occasional headache, nausea Not reported
120 -125 Headache, nausea, cramps, confusion 23
115-120 Agitation, drowsy, stupor 30
lt115 Seizures, coma 40
26Step 1 Assess Volume status
- Mucosal membranes, tongue, skin turgor, urine
output
27Step 2 CLASSIFY
- Hyper-volaemic
- Normo-volaemic
- Hypo-volaemic
Weight Down OK Up
28Step 3 Evaluate Clinical
29Step 4 Evaluate Laboratory
Conserving sodium
Losing sodium in urine
30Management 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
31Tolvaptan
- 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
32Secondary care
- Special tests
- Hypertonic saline test
- Water loading tests
- Measurement of AVP
- Hypertonic saline infusions Na rise not
gt10mmol/d - Scans, etc
DDI Dipsogenic DI
33Summary 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!
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35Hypernatraemia Nagt145
- History
- Thirst/ Polyuria
- No symptoms
- Drugs
- Examination
- Dehydrated
Think diabetes insipidus
36Algorithm Na
Loss of water
Loss of water
37Hypokalaemia
- History
- Diarrhoea, vomiting
- No symptoms
- Drugs eg Ventolin, diuretics, insulin
- Examination
- Fluid status
- Blood pressure
Think diuretics
38Cola drink hypokalaemia
- Sugar
- Caffeine
- At least 2 litres/day
39Hypertension low K
- Think Conn
- (Hyper-aldosteronism)
- Think Cushing
- Think renal artery stenosis
Renin Aldo ratio
40Algorithm K
Gut loss
Renal loss
41Hyperkalaemia Kgt5.0
- History
- Renal
- No symptoms
- Drugs eg ACE-I, spiro, amiloride
- Examination
- Addisons
- Renal
Think renal failure
Dont forget haemolysed samples, old samples
42Algorithm
Output
Input
Dont forget Addison
43Hypercalcaemia Cagt2.6
- Mild hypercalcaemia (Ca lt3mmol)
- Mostly due to primary hyperparathyroidism
- Usually asymptomatic
- Diagnosis Ca blood/ urine PTH
44Recommending PTH-ectomy
- Patient fit for surgery
- Significantly reduced BMD on DEXA scan
- Reduced renal function (eGFR)
- Cagt2.85
- History of stones
- Increased Ca excretion
Frail elderly consider bisphosphonate infusion
45Moderate-severe Ca
- Consider malignancy esp older patient
- Myeloma
- Sarcoidosis
- Thyrotoxicosis
- FHH
- Drugs
Bisphosphonates
46Malignant hypercalcaemia
Tumour mets
Non-metastatic (PTH-RP)
47Algorithm
48Low calcium Ca lt2.2mmol
- Usually Vitamin D deficiency (30 elderly, 90
Asians?) - May be Chronic renal failure
- HypoPTH
- PseudohypoPTH
- (Low Mg)
Lack of sun
Phytate in chipatis
Housebound
49High Ca High PTH
Low Ca High PTH
High Ca Low PTH
Low Ca Low PTH
50Assessment Ca
- History
- Diet/ diarrhoea/ mal-absorption
- Thyroid surgery
- Drugs eg phenytoin
- Examination
- Tetany, Chvostek
- Renal
- Investigations
- Ca/P/ Alk Pase/ Vit D/ PTH
51Treatment Vit D deficiency
- Calciferol (D2)
- Ex Calcium Vit D 400u bd
- Colecalciferol (D3)
- Ex Adcal-D3 (400) bd
- Ergocalciferol
- 10,000 u (mal-absorption)
- Analogues
- Ex One Alpha 0.25mcg (renal failure)
Pure vitamin D (Boots, Tesco, Holland
Barrets 25mcg (1000u) od (treat)
10 mcg (400u) od (maintain)
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