Hypophosphatemia%20-and-%20hyperphosphatemia Treatment

• Presence of signs and symptoms suggestive of phosphate deficiency
  • Most important consideration 
• Estimated severity of cellular phosphate deficit
• Overall clinical status of the patient
• Renal insufficiency, simultaneous administration of intravenous (IV) glucose or hyperalimentation solutions
• Risk of aggravating coexistent hypocalcemia

Hyperphosphatemia

• In an asymptomatic patient with normal renal function, hyperphosphatemia usually resolves spontaneously as the excess phosphate is excreted
• In symptomatic patients with impaired renal function, management includes:
  • Dietary phosphate intake restriction
  • Use of phosphate-lowering therapy (eg calcium-based and non-calcium based)
  • In patients with CKD grade 5, intensified dialysis schedule should be done
• Phosphate-lowering therapies should be given in patients with CKD when there is progressive or persistent hyperphosphatemia and are not to be used as prophylaxis

• Correction of hypocalcemia and its complications
  • Calcium has potential to accelerate metastatic calcification

• Resolve underlying cause
• Resolution of symptoms
• Maintain serum calcium level within the normal reference range

Hypophosphatemia

Phosphate

Intravenous (IV) 

• In patients without severe renal insufficiency or hypocalcemia, IV phosphate at a rate of 2-8 mmol/hr of elemental phosphorous over 4-8 hours often corrects hypophosphatemia without inducing hyperphosphatemia or hypocalcemia
• Monitor serum calcium and phosphate every 6-12 hours during and after phosphate therapy
• Recurrent hypophosphatemia within 24-48 hours of apparently successful replacement may require additional infusions

Oral 

• In patients with less acute or severe hypophosphatemia, oral (or enteral) phosphate supplements are generally given as a total of 1-2 g/day in 3-4 divided doses
• It may cause gastrointestinal symptoms eg nausea or diarrhea
• Monitor serum phosphate 2-12 hours after the last dose of phosphate therapy

Hyperphosphatemia

Oral Phosphate Binders

• Most commonly used are calcium binders (eg Calcium acetate, Calcium carbonate, Calcium citrate), anion exchange resins (eg Sevelamer carbonate, Sevelamer hydrochloride), Lanthanum carbonate, Aluminum hydroxide
• Administered to decrease gastrointestinal (GI) absorption of phosphorous in patients with chronic hyperphosphatemia
• Patients who have CKD stage 4 or 5 who are not on dialysis: Treatment options include calcium-based phosphate binders and non-calcium based binders eg Sevelamer, Lanthanum
• Patients with CKD stage 5 currently undergoing dialysis: Treatment options include calcium-based phosphate binders and non-calcium based binders eg Sevelamer, Lanthanum
• Calcium-containing phosphate binders may increase calcium-phosphate product and induce vascular calcium deposition
  • Dose of calcium-based phosphate binders in patients with CKD grades 3-5 is suggested to be restricted
• Resin binders (eg Sevelamer) promote excretion of phosphorous without affecting calcium
• Avoid aluminum-containing phosphate binders in patients with renal failure
• Further studies are needed to prove the efficacy and safety of magnesium salts for patients with hyperphosphatemia
  • Several studies reported hypercalcemia and magnesium accumulation with magnesium salt treatment

Diuretics

• Those that act on the proximal tubules (eg Acetazolamide) may be considered to promote renal phosphate excretion

Hypophosphatemia

• In most asymptomatic patients, serum phosphate level spontaneously normalizes within several days when factors that trigger hypophosphatemia are corrected
• Dairy products (eg skim milk) supply absorbable calcium that help avoid hypocalcemia that may result from more aggressive replacement therapies

Hyperphosphatemia

Diet

• Foods that are high in phosphorus (eg meat, poultry, fish, eggs, dairy products, nuts, legumes) should be avoided
• According to National Kidney Foundation Kidney Disease Outcomes Quality Initiative (NKF/KDOQI) guidelines, 800-1000 mg/day should be the restriction for dietary phosphorus
• It is suggested that dietary phosphate intake be limited in patients with CKD grades 3-5 in the treatment of hyperphosphatemia only or in combination with other treatments
  • In making dietary recommendations, phosphate sources (eg animal, vegetable, additives) should be assessed substantially and patient education be given
  • Adequate protein intake should not be compromised in the restriction of dietary phosphate

Dialysis 

• Hemodialysis or peritoneal dialysis is indicated for severe refractory cases and for patients with renal failure
• Continuous venovenous hemodiafiltration is considerably effective than intermittent hemodialysis to address the slow rate of phosphate mobilization from intracellular stores