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DOH Renal, Fluids & Electrolytes Practice Questions
This topic combines fluid balance, electrolyte imbalances and kidney care, including dialysis. Many questions include a lab value to interpret. Below are 5 free sample questions for the DOH Registered Nurse exam, each with the answer and a rationale.
What this topic covers
- Fluid balance, dehydration and overload
- Potassium, sodium, calcium and magnesium imbalances
- Acid-base interpretation
- Acute kidney injury and chronic kidney disease
- Haemodialysis fistula care and peritoneal dialysis
- Catheter care and UTI prevention
The full bank has 100 renal, fluids & electrolytes questions, part of 1,500 questions across 16 nursing topics.
Free DOH renal, fluids & electrolytes questions
1. When completing a fluid balance chart, which of the following should be recorded as output?
- A. Intravenous antibiotic infusions
- B. Nasogastric tube feeds
- C. Mouth care rinses that are spat out unmeasured
- D. Vomitus and wound drainage
Show answer and rationale
Output includes urine, vomitus, diarrhoea, drainage from wounds and tubes, and gastric aspirate. IV infusions and enteral feeds are intake.
Reference: Potter & Perry Fundamentals – intake and output
2. Which finding indicates fluid volume excess?
- A. Weak, thready pulse
- B. Raised jugular venous pressure and peripheral oedema
- C. Sunken eyes and dry mucous membranes
- D. Rising haematocrit
Show answer and rationale
Fluid overload causes raised JVP, oedema, bounding pulse, crackles and weight gain. The other options reflect dehydration.
Reference: Lewis Medical-Surgical Nursing – fluid volume excess
3. Which is the main clinical use of albumin as an intravenous fluid?
- A. Routine maintenance fluid for all patients
- B. Correcting hypoglycaemia
- C. Treating hypernatraemia
- D. Expanding plasma volume by drawing fluid into the vessels
Show answer and rationale
Albumin is a colloid that raises plasma oncotic pressure, pulling fluid into the intravascular space; it is used in specific situations such as some cases of hypovolaemia or hypoalbuminaemia.
Reference: Standard IV therapy – colloids
4. Laboratory results in a dehydrated patient are most likely to show:
- A. Low haematocrit and low urine specific gravity
- B. Low serum osmolality
- C. Raised haematocrit and high urine specific gravity
- D. Low serum urea
Show answer and rationale
Haemoconcentration raises the haematocrit, serum osmolality and urea, and the kidneys conserve water, producing concentrated urine with high specific gravity.
Reference: Lewis Medical-Surgical Nursing – fluid volume deficit
5. A patient is due for a CT scan with intravenous contrast. Which finding should the nurse report to the prescriber before the scan?
- A. Blood glucose 6.2 mmol/L
- B. Allergy to adhesive tape
- C. Heart rate 78/min
- D. Raised serum creatinine
Show answer and rationale
Contrast media are nephrotoxic; a raised creatinine suggests impaired kidney function and increased risk of contrast-induced kidney injury, so preventive measures such as hydration may be needed.
Reference: Lewis Medical-Surgical Nursing – diagnostic studies of the urinary system
Study tip
Memorise the normal potassium range and the ECG changes of high potassium. It is one of the most common exam questions.
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