How to replenish intracellular stores?

From the Guidelines

To replenish intracellular stores, it is crucial to provide initial generous potassium, magnesium, calcium, and phosphate supplements with feeding at around 10 kcal/kg/day in very high risk groups, along with thiamine and other B vitamins intravenously, to prevent refeeding syndrome and ensure proper electrolyte balance. When commencing feeds in patients who have recently starved, there is a danger of inducing refeeding syndrome, which can lead to cardiac and respiratory failure, lethargy, confusion, coma, and even death 1.

To avoid refeeding problems, feeding should start at very low levels, approximately 10 kcal/kg/day, while generously supplementing and closely monitoring potassium, magnesium, calcium, and phosphate levels 1. It is also essential to correct electrolyte abnormalities before feeding starts, but this should be done simultaneously with feeding to encourage transmembrane transfer and correct intracellular electrolyte deficits 1.

Key considerations for replenishing intracellular stores include:

• Providing generous potassium, magnesium, calcium, and phosphate supplements
• Starting feeds at low levels, around 10 kcal/kg/day
• Closely monitoring electrolyte levels
• Administering thiamine and other B vitamins intravenously
• Addressing underlying causes of depletion, such as malabsorption issues or excessive losses
• Regular monitoring of electrolyte levels to avoid overcorrection and potential toxicity 1.

Intracellular repletion takes time, typically 3-7 days, as these electrolytes must cross cell membranes, and adequate hydration is essential for proper electrolyte distribution 1. By following these guidelines, healthcare providers can help prevent refeeding syndrome and ensure proper replenishment of intracellular stores in malnourished patients.

From the FDA Drug Label

Potassium depletion will occur whenever the rate of potassium loss through renal excretion and/or loss from the gastrointestinal tract exceeds the rate of potassium intake If potassium depletion associated with metabolic alkalosis cannot be managed by correcting the fundamental cause of the deficiency, e.g., where the patient requires long-term diuretic therapy, supplemental potassium in the form of high potassium food or potassium chloride may be able to restore normal potassium levels.

• To replenish intracellular stores, supplemental potassium may be used, in the form of:
  • High potassium food
  • Potassium chloride
  • Other potassium salts such as potassium bicarbonate, potassium citrate, potassium acetate, or potassium gluconate (in specific circumstances, e.g., patients with renal tubular acidosis) 2

From the Research

Replenishing Intracellular Stores

To replenish intracellular stores, it is essential to understand the mechanisms of magnesium homeostasis. Magnesium is the second most abundant intracellular cation and plays a crucial role in various enzymatic reactions involving energy metabolism and protein and nucleic acid synthesis 3, 4, 5.

• Magnesium Intake and Absorption: Magnesium is absorbed uniformly from the small intestine, and its serum concentration is controlled by excretion from the kidney 3.
• Treatment of Magnesium Deficiency: Intravenous or oral magnesium repletion is the main treatment for magnesium deficiency 6.
• Regulation of Magnesium Homeostasis: The kidneys are the key regulators of magnesium homeostasis by limiting urinary excretion to less than 4% while the gastrointestinal tract loses over 50% of the magnesium intake in the feces 4.
• Causes of Hypomagnesemia: Hypomagnesemia may be caused by reduced intake, reduced absorption, redistribution, or increased excretion of magnesium 3.
• Assessment of Magnesium Status: The clinical laboratory evaluation of magnesium status is primarily limited to the serum magnesium concentration, 24-hour urinary excretion, and percent retention following parenteral magnesium 3. However, these tests do not necessarily correlate with intracellular magnesium.

Key Considerations

• Magnesium deficiency can cause various symptoms, including weakness, tremors, seizures, cardiac arrhythmias, hypokalemia, and hypocalcemia 3.
• Hypermagnesemia is primarily seen in acute and chronic renal failure and is treated effectively by dialysis 3, 4.
• A large segment of the population may have an inadequate intake of magnesium, leading to chronic latent magnesium deficiency, which has been linked to various diseases, including atherosclerosis, myocardial infarction, hypertension, cancer, kidney stones, premenstrual syndrome, and psychiatric disorders 3.