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Renal YR3 > Electrolytes and Fluid Balance > Flashcards

Electrolytes and Fluid Balance Flashcards

(42 cards)

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1
Q

What is hypernatraemia often due to?

A

Water deficit

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2
Q

Consequences of hypernatraemia

A
  • Cellular dehydration
  • Vascular shear stress - bleeding and thrombosis
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3
Q

Symptoms of hypernatraemia

A
  • Thirst
  • Apathy
  • Irritable
  • Weakness
  • Confusion
  • Reduced conc
  • Seizures
  • Hyperreflexia
  • Spasticity
  • Coma
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4
Q

Causes of hypovolaemic hypernatraemia

A

Renal water loss:
* osmotic diuresis (via NG feeding),
* loop diuretics
* intrinsic renal disease
Non-renal water loss:
* excess sweating
* burns
* diarrhoea
* fistulas

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5
Q

Cause of euvolaemic hypernatraemia

A

Renal:
* Diabetes insipidus
* Hypodipsia (no thirst mechanism)

Extra renal:
* Insensible - skin, resp, stool
* Respiratory losses

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6
Q

Causes of hypervolaemic hypernatraemia

A
  • Primary hyperaldosteronism
  • Cushing syndrome
  • Hypertonic dialysis
  • Hypertonic sodium bicarbonate
  • Sodium chloride tablets
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7
Q

Diabetes insipidus differential

A

Psychogenic polydipsia

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8
Q

Urine in diabetes insipidus

A

Dilute - osmolality of <300

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9
Q

Diabetes insipidus symptoms

A
  • Polydipsia
  • Polyuria
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10
Q

Na+ in diabetes insipidus

A

Not always hypernatraemic
If are will be euvolaemic

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11
Q

What are two types of diabetes insipidus?

A

Cranial - impaired release of ADH
Renal - impaired response/resistance to ADH

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12
Q

Causes of cranial diabetes insipidus

A
  • Trauma/post op
  • Cerebral sarcoid/TB
  • Infection - meningitis/encephalitis
  • Cerebral vasculitis (SLE/Wegener’s)
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13
Q

Causes of renal diabetes insipidus

A
  • Congenitial
  • Drugs (lithium, amphotericin, demeclocyline)
  • Hypokalaemia
  • Hypercalcaemia
  • Tubulointerstitial disease
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14
Q

Treatment for hypernatreamia

A

Free water

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15
Q

Hyponatraemia symptoms

A
  • Decreased perception
  • Gait distubance
  • Yawning
  • Nausea
  • Reversible ataxia
  • Headache
  • Apathy
  • Confusion
  • Seizures
  • Coma
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16
Q

What causes psuedohyponatraemia?

A

Occurs with:
* high lipids
* myeloma
* hyperglycaemia
* uraemia

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17
Q

Investigations for hyponatraemia

Study These Flashcards
A
  • Plasma osmolality - if normal or raised then pseudohyponatraemia
  • K+ and Mg levels - Hypokalaemia/hypomagnesia potentiates ADH release
  • Urine sodium - if less than 20 non renal loss, >40 = SIADH
  • TSH
  • 9am cortisol
  • Calcium
  • Albumin
  • Glucose
  • LFT
  • CT head/chest if suspect SIADH
18
Q

How to assess whether hypovolaemic hyponatraemia is renal or non renal loss?

Study These Flashcards
A

Urine Na+
If more than 20mmol/L - renal loss
If Less than 20 - non renal loss

19
Q

Renal losses causing hypovolaemic hyponatraemia

Study These Flashcards
A
  • Diuretics - thiazides
  • Osmotic diuresis (glucose, urea in recovering acute tubular necrosis)
  • Addisons disease
20
Q

Non-renla losses causing hypovolaemic hyponatraemia

Study These Flashcards
A
  • Diarrhoea
  • Vomitting
  • Sweating
  • Third space losses - burns, bowel obstruction, pancreatitis
21
Q

Treatment for hypovolaemic hyponatraemia

Study These Flashcards
A
  • IV fluids - 0.9% saline at 1-3ml/kg/hr
  • Give K+ if needed
22
Q

Causes of eurvolaemic hyponatraemia

Study These Flashcards
A
  • Hypothyroidism
  • Primary polydipsia (if urine osmolality less than 100)
  • Glucocorticoid deficiency - adrenal insifficiency
  • SIADH
23
Q

SIADH findings

Study These Flashcards
A
  • Low serum osmolality
  • Concentrated urine - inapporpirate greater than 100
  • Urine Na is more than 20
  • Euvolaemia
  • NOt on diuretics
  • Elimination diagnosis - normal renal, thyroid, adrenal function
24
Q

Management SIADH

Study These Flashcards
A
  • Fluid restrict less than 800ml per day
  • PO sodium chloride
  • Furosemide?
  • Demeclocycline induces diabetes insipidus (reverse)
  • Tolvaptan alternatively
25
Causes of hypervolaemic hyponatraemia
* CHF * Nephrotic syndrome * Liver cirrhosis
26
Treatment of hypervolaemic hyponatraemia
* Fluid restrict * Consider furosemide
27
Risk of correcting hyponatraemia too fast
* Pontine/osmotic myelinosis * Aim to correct less than 12mmol/L/day
28
general acute treatment of hyponatraemia
* If within 48hrs and symptomatic * Give 3% hypertonic saline IV boluses +/- furosemide
29
Usual causes of acute hyponatraemia
* Iatrogenic * Polydipsia * Colonoscopy prep * Ecstasy
30
Treatment for chronic hyponatraemia
If >48hrs and symptomatic * hypertonic saline boluses if seizing * Otherwise isotonic saline and furosemide - aim to correct 8mmol/L in 24hrs * If chronic and asymptomatic - water restrict, stop offending drug, if dehydrated restore volume, if overloaded Na and water restriction and diuretics
31
Causes of hyperkalaemia
* CKD or K+ rich diet + CKD * Drugs - ACEi, ARBs, Spironolactone, amiloride, NSAIDs, LMWH, heparin * Hypoaldosteronism * Addisons disease * Acidosis * Massive tissue damage - tumour lysis, burns, haemolysis, rhabdomyolysis * Psuedohyperkalaemia - haemolysed blood sample
32
Rarer cause of hyperkalaemia
* Hyperkalaemic periodic paralysis * Gordons syndrome
33
ECG changes in hyperkalaemia
* Tall tented T waves * P wave flattened * Prolonged QRS * Slurred ST segment * Asystole?
34
Treatment for hyperkalaemia steps
1. Stabilise myocardium 2. Shift K+ into cells 3. Eliminate K+ from body
35
Stabilise myocardium treatment
10 mls of 10% calcium gluconate over 5-10 minutes
36
Shifting K+ back into cells treatment
* 10 units of IV fast acting insulin * And IV glucose/dextrose 50% 50mls * 500mls of 1.4% Sodium bicarbonate (only effective it pt acidotic) * 5-10mg Salbutamol nebuliser
37
Eliminating K+ from body treatment
* Calcium resonium - 15-45g oral or rectal mixed with sorbitol or lactulose * Furosemide 20-80mg depending on hydration * Dialysis - if resistant to medical treatment
38
Symptoms of hypokalaemia
* Fatigue * Confusion * Proximal muscle weakness * Paralysis * Cardiac arrhtymias * Worsened glucose control in diabetics * Hypertension
39
Causes of hypokalaemia
* Pseudohypokalaemia - acute leukaemia * Vomitting + diarrhoea * Conns syndrome * Cushing syndrome * Diuretics
40
ECG changes in hypokalaemia
* Small T waves * U wave (after T wave) * Increased PR interval
41
Treatment for hypokalaemia
Replace magnesium Oral K+ replacement IV K+ replacement (usually in 0.9% saline avoid in dexrose as induces further hypokalaemia) | Insulin secreted when dextose given = K+ into cells
42

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