Diabetes mellitus and electrolyte disorders

Table 1 Principal causes of electrolyte disorders in diabetic patients

Sodium disorders1

Hyponatremia

Pseudohyponatremia (marked hyperlipidemia)

Hyperglycemia (hypertonicity)-induced movement of water out of the cells (dilutional hyponatremia)

Osmotic diuresis-induced hypovolemic hyponatremia

Drug-induced hyponatremia: hypoglycemic agents (chlorpropamide, tolbutamide, insulin) or other medications (e.g., diuretics, amitriptyline)

Pseudonormonatremia (marked hyperlipidemia, severe hypoproteinemia)

Hypernatremia

Pseudohypernatremia (severe hypoproteinemia)

Loss of water in excess of sodium and potassium (osmotic dieresis), if this water loss is replaced insufficiently

Potassium disorders

Hypokalemia

Shift hypokalemia: insulin administration

Gastrointestinal loss of K+: malabsorption syndromes (diabetic-induced motility disorders, bacterial overgrowth, chronic diarrheal states)

Renal loss of K+: osmotic diuresis, hypomagnesemia, diuretics (thiazides, thiazide-like agents, furosemide)

Hyperkalemia

Shift hyperkalemia: acidosis, insulin deficiency, hypertonicity, rhabdomyolysis, drugs (e.g., beta blockers)

Reduced glomerular filtration of K+: acute and chronic kidney disease

Reduced tubular secretion of K+: hyporeninemic hypoaldosteronism, drugs (angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers, renin inhibitors, beta blockers, potassium-sparing diuretics)

Magnesium disorders

Hypomagnesemia

Pseudohypomagnesemia: hypoalbuminemia

Shift hypomagnesemia: insulin administration

Poor dietary Mg2+ intake

Gastrointestinal Mg2+ losses: diarrhea as a result of diabetic autonomic neuropathy

Increased renal Mg2+ losses due to osmotic diuresis, glomerular hyperfiltration, diuretic administration

Recurrent metabolic acidosis

Calcium disorders

Hypocalcemia

Pseudohypοcalcemia: hypoalbuminemia2

Acute renal failure due to accompanying hyperphosphatemia

Advanced chronic renal insufficiency due to hyperphosphatemia and low levels of vitamin D

Nephrotic syndrome: loss of 25-hydroxyvitamin D3 and its binding protein in the urine

Hypomagnesemia

Vitamin D deficiency

Drug-mediated: loop diuretics

Hypercalcemia

Concurrent hyperparathyroidism

Thiazide therapy

Phosphorus disorders

Hypophosphatemia

Osmotic diuresis

Drugs: thiazides, loop diuretics, insulin

Malabsorption syndromes

Primary hyperthyroidism

Vitamin D deficiency

¹Spurious sodium disorders occur when sodium is measured with indirect ion-selective electrodes;

²The ionized serum calcium levels are normal.