This deLYTEful ring-bound handbook stands out clearly among the many texts and learning aids that attempt to teach us and our students more about renal and electrolyte disturbances. Dr Mitchell Halperin's expertise in this field is widely acknowledged and is only equaled by his enthusiasm in teaching others concepts he has perceived in the mass of laboratory data that is modern medicine.
Each of the text's six chapters has pearls of wisdom, clinical classifications and syndromes, and, finally, elements of differential diagnosis. Each chapter is accompanied by at least one clinical case applicable to the metabolic abnormality discussed, eg, hypernatremia after a skull fracture in a patient who, after all, did not have diabetes insipidus but, rather, urea-induced osmotic diuresis. Both at the beginning of the book and at intervals thereafter, Halperin defines and discusses the transtubular potassium gradient (TTKG), with emphasis on practicality. The TTKG reflects urine potassium/plasma potassium