eMedicine Specialties > Pediatrics: General Medicine > Endocrinology

Hypophosphatemic Rickets: Follow-up

Author: Karl S Roth, MD, Professor and Chair, Department of Pediatrics, Creighton University School of Medicine
Coauthor(s): James CM Chan, MD, Professor of Pediatrics, University of Vermont College of Medicine; Director of Research, The Barbara Bush Children's Hospital, Maine Medical Center
Contributor Information and Disclosures

Updated: Feb 6, 2009

Follow-up

Further Inpatient Care

  • Healing of the rachitic changes typically occurs within 6-8 weeks of instituting treatment. During this time, maintain the calcitriol within the recommended dosage to maintain serum calcium and phosphate levels within reference ranges. Monitor these levels weekly over the first 2-3 months of treatment. Urinary calcium and phosphate excretion monitoring also are important.
  • The patient's requirements for calcium deposition and vitamin D to expedite the healing process diminish as healing progresses; thus, the patient with hypophosphatemic rickets becomes highly susceptible to hypercalcemia during this phase. Consider reducing the calcitriol dosage at this time, guided by the weekly calcium and phosphorus measurements, until a reduced and stable dosage is reached.

Inpatient & Outpatient Medications

  • Calcitriol
  • Neutralized, buffered phosphate solution
  • Hydrochlorothiazide
  • Amiloride
  • Human recombinant growth hormone

Complications

  • An outstanding feature of familial hypophosphatemic rickets is short stature. The short stature associated with this condition is disproportionate, resulting from deformity and growth retardation of lower extremities. This short stature has been addressed in clinical trials by adding growth hormone (GH) to the usual treatment protocol to stimulate growth plates in the long bones. At least one study has reported a mild degree of disproportionate truncal growth, which requires further evaluation. Although GH therapy has been effective in promoting short-term growth, its high cost discourages widespread use. As a result, many properly treated children ultimately achieve less-than-average height.
  • Acute hypercalcemia (with resulting irritability, confusion, and potential seizures) can occur during treatment. Nephrocalcinosis, the long-term result of overaggressive therapy, may be more damaging. Although ultrasonography reveals that 47% of properly treated patients show evidence of nephrocalcinosis, the condition apparently does not progress to renal failure.
  • Hypertension has been reported in older children under treatment as a consequence of persistent hyperparathyroidism. Nephrocalcinosis did not need to be present for hypertension to occur. Consequently, patients under treatment should be carefully monitored for laboratory signs of hyperparathyroidism.

Prognosis

  • Apart from the short stature of most affected adults, the prognosis for a normal lifespan and normal health is good.

Patient Education

  • Provide genetic counseling following initial diagnosis to help an affected child's parents understand the hereditary basis of the condition. Counseling must be provided with sensitivity to avoid family conflict.
  • The patient and family need to know the importance of close follow-up to avoid complications.
  • Unless a concomitant GH deficiency is observed, administration of biosynthetic GH for growth promotion has not been approved. Only preliminary evidence of improved final height with GH therapy has been reported.

Miscellaneous

Medicolegal Pitfalls

  • The physician must be keenly aware of the differences in serum phosphate reference ranges for infants and adults to avoid missing the primary diagnostic indicator. Misdiagnosis of the etiology significantly delays healing in patients with hypophosphatemic rickets.
  • A linear correlation has been noted between the mean phosphate supplementation and the degree of nephrocalcinosis; more than 150 mg/kg/d markedly increases the severity of calcium deposition. Thus, the dose should not exceed 100 mg/kg/d; the recommended amount is 50 mg/kg/d.
 


More on Hypophosphatemic Rickets

Overview: Hypophosphatemic Rickets
Differential Diagnoses & Workup: Hypophosphatemic Rickets
Treatment & Medication: Hypophosphatemic Rickets
Follow-up: Hypophosphatemic Rickets
References
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References

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Further Reading

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Keywords

hypophosphatemic rickets, familial hypophosphatemic rickets, vitamin D-resistant rickets, X-linked hypophosphatemic rickets, X-linked hypophosphatemic osteomalacia, rachitic disease, vitamin D ingestion, vitamin D–resistant rickets, hypophosphatemia, proteolysis, hyperphosphaturia, short stature, dental abscess, delayed dentition, bone deformation, cranial synostosis, short stature

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Contributor Information and Disclosures

Author

Karl S Roth, MD, Professor and Chair, Department of Pediatrics, Creighton University School of Medicine
Karl S Roth, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Pediatrics, American College of Nutrition, American Pediatric Society, American Society for Clinical Nutrition, American Society of Nephrology, Association of American Medical Colleges, Medical Society of Virginia, New York Academy of Sciences, Sigma Xi, Society for Pediatric Research, and Southern Society for Pediatric Research
Disclosure: Nothing to disclose.

Coauthor(s)

James CM Chan, MD, Professor of Pediatrics, University of Vermont College of Medicine; Director of Research, The Barbara Bush Children's Hospital, Maine Medical Center
James CM Chan, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Pediatrics, American Association of University Professors, American Chemical Society, American Heart Association, American Medical Association, American Physiological Society, American Society for Bone and Mineral Research, American Society of Nephrology, American Society of Pediatric Nephrology, International Society of Nephrology, New York Academy of Sciences, Society for Experimental Biology and Medicine, and Southern Society for Pediatric Research
Disclosure: Nothing to disclose.

Medical Editor

Arlan L Rosenbloom, MD, Adjunct Distinguished Service Professor Emeritus of Pediatrics, University of Florida; Fellow of the American Academy of Pediatrics; Fellow of the American College of Epidemiology
Arlan L Rosenbloom, MD is a member of the following medical societies: American Academy of Pediatrics, American College of Epidemiology, American Pediatric Society, Endocrine Society, Florida Pediatric Society, Lawson-Wilkins Pediatric Endocrine Society, and Society for Pediatric Research
Disclosure: Nothing to disclose.

Pharmacy Editor

Mary L Windle, PharmD, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy, Pharmacy Editor, eMedicine
Disclosure: Pfizer Inc Stock Investment from financial planner; Avanir Pharma Stock Investment from financial planner ; WebMD Salary and stock Employment and investment from financial planner

Managing Editor

George P Chrousos, MD, FAAP, MACP, MACE, FRCP(London), Professor and Chair, First Department of Pediatrics, Athens University Medical School, Aghia Sophia Children's Hospital, Greece
George P Chrousos, MD, FAAP, MACP, MACE, FRCP(London) is a member of the following medical societies: American Academy of Pediatrics, American College of Endocrinology, American College of Physicians, American Pediatric Society, American Society for Clinical Investigation, Association of American Physicians, Endocrine Society, Lawson-Wilkins Pediatric Endocrine Society, and Society for Pediatric Research
Disclosure: Nothing to disclose.

CME Editor

Merrily P M Poth, MD, Professor, Department of Pediatrics and Neuroscience, Uniformed Services University of the Health Sciences
Merrily P M Poth, MD is a member of the following medical societies: American Academy of Pediatrics, Endocrine Society, and Lawson-Wilkins Pediatric Endocrine Society
Disclosure: Nothing to disclose.

Chief Editor

Stephen Kemp, MD, PhD, Professor, Department of Pediatrics, Section of Pediatric Endocrinology, University of Arkansas and Arkansas Children's Hospital
Stephen Kemp, MD, PhD is a member of the following medical societies: American Academy of Pediatrics, American Association of Clinical Endocrinologists, American Pediatric Society, Endocrine Society, Phi Beta Kappa, Southern Medical Association, and Southern Society for Pediatric Research
Disclosure: Genentech, Inc. Honoraria Speaking and teaching; Pfiser, Inc. Honoraria Consulting

 
 
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