Vitamin D Deficiency and Rickets

Vitamin D Deficiency and Rickets:

Vitamin D

• Prevalence of deficiency and insufficiency: 15% of the pediatric population.
• Vitamin D Physiology

• Daily recommended intake(healthy individuals)
  • Infants (soon after birth): 400 IU/day
  • 1-18 years: 600IU/day
• Definitions of sufficiency, insufficiency, and deficiency
  • Vitamin D sufficiency: 20 to 100 ng/mL
  • Vitamin D insufficiency: 12 to 20 ng/mL
  • Vitamin D deficiency: <12 ng/mL
• Risk factors for deficiency
  • Nutritional deficiency: maternal Vit D deficiency, a diet deficiency, exclusive breastfeeding
  • Malabsorption: celiac disease, inflammatory bowel disease, cystic fibrosis
  • 25-hydroxylase deficiency: liver disease, genetic disease
  • 1,25-hydroxylase deficiency: renal disease, genetic disease
  • Increased metabolism of Vitamin D-use of anti-seizure meds, steroids
  • Other: CYP34A deficiency, Vitamin D binding protein deficiency, and obesity
• Clinical manifestations:
  • Rickets in growing children.
  • Severe vitamin D deficiency may lower serum phosphorus levels–> muscle weakness.

 

• Evaluation:
  • 25 hydroxyvitamin D levels in the high-risk population.
• Treatment of mild vitamin D deficiency-cholecalciferol (D3) or ergocalciferol(D2)
  • <12 months old – 1000 IU/day for 6 to 12 weeks, followed by maintenance dosing of at least 400 IU/day for 3 to 6 months
  • ≥12 months old – 2000 IU/day for 6 to 12 weeks, followed by maintenance dosing of 600 to 1000 IU/day for 3-6 months

 

 

Rickets

Definition: it refers to the changes at the growth plate caused by the deficient mineralization of bone before the closure of the growth plates.

 

1. Calcipenic rickets: phosphorus concentration is normal or low, along with elevated PTH levels.
2. Phosphopenic rickets: phosphorus level is low with normal PTH concentrations.

 

• Evaluation:
  • Calcium, albumin, phosphorus, 25 hydroxyvitamin D levels, 1-25 dihydroxy vitamin D levels, PTH, spot urinary calcium/creatinine, alkaline phosphatase levels.
  • Radiological:  X-ray of wrists.

 

Anticipatory Laboratory Values for different types of Rickets

 

Parameters	Ca2	Po4	PTH	Alk Phos	25(OH) Vit D	1,25(OH2) Vit D
Vitamin D deficiency	↓/↔	↓/↔	↑	↑	↓	↔
1 alpha-hydroxylase def	↓	↓/↔	↑	↑	↔	↓
Vitamin D Resistant	↓	↓/↔	↑	↑	↔	↑↑
Hypophosphatemic rickets	↔	↓↓	↔	↑	↔	↔

 

• Treatment: It depends on the type of Rickets.
  • Chole/Ergocalciferol-1000-9,000IU/day for Vitamin D deficiency rickets.
  • Add calcium at a dose of 30-75mg/kg/day if hypocalcemia is present.
  • Vitamin D resistant and 1 alpha-hydroxylase rickets are treated with calcitriol.
  • For the treatment of hypophosphatemic rickets, calcitriol(higher dose) is given along with phosphorus supplementation.
  • Monitoring requires monitoring of calcium, phosphorus, alkaline phosphatase, and parathyroid hormone levels in 2-3 weeks.

References and Resources

• Munns CF, Shaw N, Kiely M, et al. Global Consensus Recommendations on Prevention and Management of Nutritional Rickets. J Clin Endocrinol Metab 2016; 101:394.
• https://www.pedsendo.org/assets/patients_families/EdMat/third_batch/Vitamin%20D%20Deficiency.pdf