Characteristic patterns of electrolyte derangement

Question 12 from the first paper of 2011 asks the candidate to "list the major biochemical abnormalities" associated with adrenal insufficiency, refeeding syndrome, tumour lysis syndrome and ethylene glycol toxicity. All of these are dealt with individually in a series of dedicated chapters (eg. tumour lysis syndrome is explored in the Haematology and Oncology section), but that does not help one categorise Question 12. In order to avoid an embarrassing breakdown of his SAQ taxonomy, the author has instead decided to compose a list of all the typical electrolyte derangement patterns which may be seen in the ICU.

Not unexpectedly, there is little reading material on this topic out there. Every man and his dog has published a review article of "electrolyte disturbance", but nobody seems to have put together a summary of commonly seen syndromes, i.e. recognisable patterns of biochemical derangement. The closest thing I have found is Martin Crook's Case Presentations in Chemical Pathology (2013) which a 150-page book, far from a summary.  Crook is an Honorary Lecturer in chemical pathology at the University of London, and this book has known several editions since its first publication in 1993, so it seems like a reasonably reliable reference. To spare the time-poor candidates, important biochemical syndromes have been extracted from this book, and listed below with minimal embellishment. Furthermore, here are links to more detailed discussions of the four specific disorders asked about in Question 12 from the first paper of 2011:

• Adrenal insufficiency
• Refeeding syndrome
• Tumour lysis syndrome
• Ethylene glycol toxicity

Endocrine disturbances

Adrenal insufficiency

• Hyponatraemia
• Hyperkalaemia
• Normal anion gap acidosis
• Hypoglycaemia
• Hypercalcaemia

Hyperaldosteronism

• Hypokalemia
• Hypernatremia
• Metabolic alkalosis

Phaeochromocytoma

• Hypokalemia (due to β-2 effect)

Sarcoidosis

• Hypercalcemia
• Hypercalciuria

Carcinoid syndrome

• Hypokalemia
• Hypomagnesemia
• Normal anion gap acidosis
  (all due to secretory diarrhoea)

Metabolic and nutritional syndromes

Refeeding syndrome

• Hypophosphataemia
• Hypokalaemia
• Hypomagnesaemia
• Hyperglycaemia

Sequelae of parenteral nutrition

• Hyperglycaemia
• Hyperlipidiaemia
• Normal anion gap metabolic acidosis

Electrolyte evidence of tissue destruction

Rhabdomyolysis

• Hyperkalemia
• Hyperphosphataemia
• Myoglobinuria
• Raised serum CK and LDH

Tumour lysis syndrome

• Hyperphosphataemia
• Hyperkalaemia
• Hypocalcaemia
• Hyperuricaemia
• High anion gap metabolic acidosis
• Raised serum LDH

Toxin syndromes

Toxic alcohols, eg. ethylene glycol

• High anion gap metabolic acidosis
• High serum osmolar gap
• Hypocalcaemia

Lithium toxicity

• Negative anion gap
• Hypernatremia

Salicylate toxicity

• High anion gap metabolic acidosis
• Hypokalemia
• High urinary potassium