Renal - Fluid And Acid-Base Status

Question 1

Outline the requirements of maintenance fluids

Answer 1

• 25-30ml/kg/day of water
• Approx 1mmol/kg/day of K+, Na+ and Cl-
• Approx 50-100g/day of glucose to limit starvation ketones

Question 2

Metabolic acidosis: what is the equation for the anion gap and what are normal range values?

Answer 2

(Na + K) - (Cl + HCO3)

Normal range values: 10-18

Question 3

Metabolic acidosis: what conditions cause a normal anion gap?

Answer 3

‘ABCD’

• Addison’s disease
• Bocarbonate loss: diarrhea, ureterosigmoidistomy
• Chloride injections (ammonium chloride)
• Drugs: acetazolamide
• renal tubular acidosis

Question 4

Metabolic acidosis: what conditions cause a raised anion gap?

Answer 4

• Raised lactate: shock, hypoxia
• Ketones: DKA, alcohol
• Urate: renal failure
• Acid poisoning: salicylates, methanol

Question 5

What occurs in metabolic alkalosis?

Answer 5

-May be caused by loss of hydrogen ions or gain of bicarbonate. It is mainly due to problems in kidney or GI tract

Question 6

Name conditions which cause metabolic alkalosis

Answer 6

• Vomiting/aspiration
• Diuretics
• hypokalaemia
• primary hyperaldosteronism
• Cushing’s syndrome

Question 7

Name conditions which cause respiratory acidosis?

Answer 7

• COPD
• Decompensation in other resp conditions: asthma, pulmonary oedema
• Sedative drugs: benzodiazepines, opiate overdose

Question 8

Name common causes of respiratory alkalosis

Answer 8

• Anxiety leading to hyperventilation
• Pulmonary embolism
• Salicylate poisoning
• CNS disorders: stroke, subarachnoid haemorrhage, encephalitis
• Altitude
• Pregnancy