Hyperphosphatemia

Etiology

  • Increased Dietary Phosphate Intake
  • Acute Kidney Injury (AKI)/Chronic Kidney Disease (CKD)
  • IV Phosphate Administration
    • Total Parenteral Nutrition (TPN)
  • Oral Phosphate Administration
    • Fleet’s Phosphosoda
  • Rectal Phosphate Administration
    • Fleet’s Enema

Physiology

Dietary Phosphorous

  • Organic Phophorous
    • Found naturaly in foods
    • Usually bound to proteins (such as phytate) that limit their intetsinal absorption
    • Organic phosphate is hydrolyzed in intestinal lumen, releasing inorganic phosphate, which is then absorbed
    • Only 60% of intestinal organic phospphate is absorbed
    • Vitamine D compounds (such as calcitriol): increase intestinal phosphate absorption
  • Inorganic Phosphorous
    • Inorganic phosphorus is commonly used as a food additive in many processed foods (chicken nuggets, hot dogs, spreadable cheeses, etc): extends shelf life, enhances flavor, improves color, retains moisture, acts as an emulsifier, etc
    • Inorganic phosphorus is not protein-bound
    • Approximately 90-100% of inorganic phosphorus is absorbed

Effects of Hyperphosphatemia

  • The potential adverse effects of high serum phosphorus (and/or phosphorus accumulation( are observed in end-stage renal disease (CKD-5), CKD-2 to CKD-4, and in the general population

Clinical Manifestations

Renal Manifestations

  • Acute Kidney Injury (AKI) (see Acute Kidney Injury, [[Acute Kidney Injury]])
    • Associated with hypocalcemia
  • Acute Phosphate Nephropathy
    • Typically irreversible
  • xxx

Other Manifestations

  • Parathyroid Hyperplasia/Hyperparathyroidism
  • Vascular Calcification
  • Cardiovascular Disease
  • Loss of Bone Strength and Bone Mass/Risk of Bone fractures

Treatment

General Commnets

  • K/DOQI Guidelines: maintaon phosphate 3.5 to 5.5 mg/dL

Limitation of Dietary Phosphorous

  • xxx

Phosphate Binders

  • Phosphate Binder Agents
    • Aluminium Hydroxide (Alucaps, Basaljel)
    • Calcium Carbonate (Calcichew, Titralac) (see Calcium Carbonate, [[Calcium Carbonate]])
    • Calcium Acetate (Lenal Ace, PhosLo) (see Calcium Acetate, [[Calcium Acetate]])
    • Lanthanum Carbonate (Fosrenol) (see Lanthanum Carbonate, [[Lanthanum Carbonate]])
    • Sevelamer (Renagel, Renvela) (see Sevelamer, [[Sevelamer]])
    • Calcium Acetate/Magnesium Carbonate (Osvaren, Lenal Ace, Renepho)
  • Indications
    • xxxx
  • COSMOS Trial ([MEDLINE]
    • Study: multicenter, open-cohort, observational prospective study in 227 dialysis centers from 20 European countries (n = 6797)
    • Main Findings
      • Use of phosphate-binding agents -> 29% lower all-cause mortality
      • Use of phosphate-binding agents -> 22% lower cardiovascular mortality
      • All single and combined therapies with phosphate-binding agents (except aluminum salts) showed a beneficial association with survival

References

  • K/DOQI clinical practice guidelines for nutrition in chronic kidney failure. K/DOQI, National Kidney Foundation. Am J Kidney Dis. 2000;35(6)(suppl 2):S17–S104
  • The dialysis outcomes and practice patterns study (DOPPS): An international hemodialysis study. Kidney Int. 2000;57(suppl 74):S74–S81
  • Mortality risk in hemodialysis patients and changes in nutritional indicators: DOPPS. Kidney Int. 2002;62:2238–2245
  • Hidden sources of phosphorus in the typical American diet: does it matter in nephrology? Semin Dial. 2003;16(3):186–188
  • K/DOQI clinical practice guidelines for bone metabolism and disease in chronic kidney disease. Am J Kid Dis. 2003;42(4):S1–S201
  • Hidden phosphorus: where do we go from here? J Ren Nutr. 2007;17(4):e31–e36
  • Is controlling phosphorous by decreasing dietary protein intake beneficial or harmful in persons with chronic kidney disease. Am J Clin Nutr. 2008;88:1511–1518
  • Mortality risk for dialysis patients with different levels of serum calcium, phosphorus, and PTH: the Dialysis Outcomes and Practice Patterns Study (DOPPS). Am J Kidney Dis. 2008;52(3):519–530
  • Understanding sources of dietary phosphorous in the treatment of patients with chronic kidney disease. Clin J Am Soc Nephrol. 2010;5:519–530
  • Use of phosphate-binding agents is associated with lower risk of mortality. Kidney Int. Published online 3 July 2013; doi:10.1038/ki.2013.185 [MEDLINE]