A seizure from hyponatremia is an emergency, and it is treated before the workup is finished. 3% saline 150 mL IV over 20 minutes is the first step (100 mL over 10 minutes in the US panel), with the sodium checked after each dose, repeated up to twice, and stopped once symptoms improve or the sodium has risen about 5 mmol/L. A peripheral IV is acceptable; waiting for central access is a delay. That rise counts toward the 24-hour limit — 10 mmol/L, or 8 if high risk.

A raises the sodium far too slowly for a patient who has just seized, and can lower it further if this proves to be SIADH. C takes days and does nothing for cerebral edema now. D inverts the priority: the osmolality and urine studies go with the first bloods, but treatment of severe symptoms never waits for them. Her normal glucose already makes hypertonic hyponatremia unlikely.

Takeaway: Severe symptoms are treated before the diagnosis is finished.

Six hours under 0.5 mL/kg/h (here 0.19) is AKI by the KDIGO urine-output criterion, even with a normal creatinine. The first question at the bedside is whether urine is being made and not reaching the bag. He has three reasons to retain — prostatic hyperplasia, an opioid, and a day after surgery — and a bladder scan answers it in two minutes. If the bladder is full, a urethral catheter treats the AKI.

A treats a volume depletion his examination does not show; a bolus is for the patient who is volume-depleted, and it would not empty a full bladder. B: KDIGO and NICE both advise against loop diuretics to treat AKI except for volume overload, and he has none. D waits eight hours on a criterion he already meets, with the cause still unknown.

Takeaway: Low urine output: scan the bladder before you give or take away fluid.

For a patient on hemodialysis, a potassium of 6.5 or more is itself the indication for urgent dialysis. The UK Kidney Association’s “still 6.5 or more despite treatment” trigger is for patients whose kidneys can still respond; his cannot. Calcium and insulin-glucose were right, and they are a bridge: the shift wears off within hours and the potassium rebounds, and up to 40% of patients on hemodialysis do not respond to salbutamol.

A removes potassium too slowly to stand in for dialysis in an anuric patient; Lokelma starts working about an hour after a dose. B needs a kidney that makes urine, and he is anuric. C spends the hours the shift has bought instead of using them to arrange dialysis.

Takeaway: On hemodialysis, hyperkalemia of 6.5 or more means call for dialysis now.

A creatinine rising during decongestion is not automatically AKI. The question is not “has the creatinine gone up?” but “is she still volume overloaded?” — and her neck veins, lungs, legs and breathing all say yes. In the DOSE secondary analysis, a creatinine rise over 26.5 µmol/L during decongestion did not predict death, readmission or emergency visits at 60 days. The diuretic continues, with daily creatinine and electrolytes.

B stops decongestion in a patient who is still congested, and leaves her breathless for a number that does not predict harm here. C is a resuscitation bolus, which is for the volume-depleted patient; in a congested one it worsens the problem. D steps down before she is decongested.

Takeaway: In heart failure, judge the creatinine against the congestion.

Every number here looks like SIADH — hypotonic, urine osmolality over 100, urine sodium over 30, no edema or orthostasis — but SIADH is a diagnosis of exclusion, and recent diuretic use excludes it. Thiazides impair free water excretion while leaving the kidney able to concentrate urine, so they produce exactly this picture. Stopping the thiazide and watching is the diagnostic move, not another test. Once it stops, check the sodium every 6 hours until stable; the rise counts toward the 24-hour limit.

A is first-line for SIADH, which cannot be diagnosed while she takes the drug that mimics it. C is for moderately severe or severe symptoms, and she has none. D is second-line for SIADH after restriction fails.

Takeaway: On a thiazide, it is not SIADH until the thiazide has been stopped.