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hyperphosphatemia

Etiology: 1) dehydration 2) increased absorption from gut (up to 45 mg/dL) a) hypervitaminosis D b) granulomatous diseases producing vitamin D 1] sarcoidosis 2] tuberculosis c) phosphorous-containing cathartics (bowel preparations) d) milk-alkali syndrome 3) phosphate-containing IV solutions 4) decreased renal excretion a) renal failure* - acute renal failure - chronic renal failure b) hypoparathyroidism - increased renal tubular reabsorption [3] c) tumoral calcinosis d) pseudoxanthoma elasticum e) infantile hyperphosphatemia f) hyperostosis g) hyperthyroidism h) growth hormone excess/acromegaly i) adrenal insufficiency j) severe hypomagnesemia 5) increased binding to serum proteins with plasma cell dyscrasias 6) increased release from bone a) osteolytic metastases to bone b) healing fractures 7) diabetes mellitus with ketosis 8) cellular release of phosphate a) rhabdomyolysis b) organ infarction c) tumor lysis syndrome d) Burkitt's lymphoma e) lymphoblastic leukemia f) metastatic small cell carcinoma g) myelogenous leukemia h) thyrotoxicosis i) acute hemolysis j) pulmonary embolism 11) portal cirrhosis 12) acid-base disorders a) metabolic acidosis including lactic acidosis b) acute respiratory acidosis 13) drugs a) androgens b) beta-blockers c) bisphosphonates - etidronate c) ethanol d) ergocalciferol e) furosemide f) growth hormone g) hydrochlorothiazide h) methicillin (occurs with nephrotoxicity) i) phosphates j) tetracycline (occurs with nephrotoxicity) k) clonidine * most common cause [3] Laboratory: 1) serum Ca+2 & serum phosphorus a) product serum Ca+2 (mg/dL) x serum phosphorus (mg/dL) > 70 indicates risk of metastatic calcification b) metastatic calification more likely to occur with elevated pH Complications: - metastatic calcification Management: 1) in the absence of renal insufficiency a) volume expansion with hypotonic saline b) aluminum-based antiacids (Amphogel) - to prevent absorption of phosphorous - more effective short term than PhosLo - low risk of metastatic calcification 2) low phosphate diet in patient with CKD4 & serum phosphate 5.3 mg/dL [3] 3) most patients with renal failure require phosphate binders [3] a) must be taken with meals to bind phosphate in foods b) phosphate binders - calcium acetate (PhosLo) - non-calcium phosphate binders associate with lower mortality [6] - sevelamer ESRD (Renagel) - lanthanum carbonate (Fosrenol) 4) hemodialysis as needed - tenapanor (Ibsrela) FDA-approved [5]

Related

inorganic phosphate; inorganic phosphorous phosphorus (inorganic phosphate) in serum

General

electrolyte disorder sign/symptom disorder of phosphorus metabolism

References

  1. Guide to Clinical Laboratory Tests, 3rd ed, NW Teitz (ed) WB Saunders, 1995
  2. Harrison's Principles of Internal Medicine, 14th ed. Fauci et al (eds), McGraw-Hill Inc. NY, 1998, pg 2262
  3. Medical Knowledge Self Assessment Program (MKSAP) 11, 16, 17, 18, 19. American College of Physicians, Philadelphia 1998, 2012, 2015, 2018, 2021.
  4. Patel L, Bernard LM, Elder GJ. Sevelamer Versus Calcium-Based Binders for Treatment of Hyperphosphatemia in CKD: A Meta-Analysis of Randomized Controlled Trials. Clin J Am Soc Nephrol. 2016 Feb 5;11(2):232-44. Review. PMID: 26668024 Free PMC Article
  5. Kuznar W FDA Panel Endorses Kidney Disease Drug for Serum Phosphorus Control. Advisors see need for alternatives, citing suboptimal efficacy and tolerance of approved options. MedPage Today. November 17, 2022 https://www.medpagetoday.com/nephrology/generalnephrology/101802
  6. NEJM Knowledge+ Nephrology/Urology