IconNon Nutritional Rickets

Rickets

  • Softening of bones because of defective mineralization of osteoid.
  • This may be due to lack of Calcium, Phosphorus, Vitamin D
  • Sources of Vit D :

  • Formation of Vit D from the skin 7 dehydro cholesterol is present in the skin layers. UV rays convert it to Vit D3 (Cholecalciferol)
  • Dietary intake of either vitamin D2 (ergocalciferol) or vitamin D3
  • Metabolism of Vit D

  • The primary absorption site for vitamin D is the jejunum.
  • First metabilosm in liver by 25 hydroxylase enzyme to form 25 OH Vit D
  • Second metabolism in Kidney by 1 alfa hydroxylase enzyme to form 1,25 Di Hydroxy Vit D Which is the Active form of Vit D
  • Actions of Vit D

  • Its major role is to maintain Serum calcium. It promotes
  • Absorption of Calcium and Phosphorus from food in the intestines
  • Reabsorption of calcium in the kidneys
  • Enabling normal mineralization of bone
  • Lack of Vit D

  • Decreases Mineralization of newly formed bone matrix (Osteoid)
  • Decreases rate of bone formation
  • Net result is less total bone & marked change in quality of bone
  • Clinical features of rickets

  • Craniotabes
  • Delayed closure of anterior fontanelle
  • Frontoparietal bossing
  • Delay in teeth eruption, enamel hypoplasia
  • Rachitic rosary
  • Harrison sulci
  • Violin case deformity of the chest
  • Enlargement of wrists
  • Progressive bowing of long bones
  • Delayed motor milestones
  • Hypotonia
  • Myopathy with normal deep tendon reflexes, and Propensity for infections (as a consequence of impaired phagocytosis and neutrophil motility)
  • Non Nutritional Rickets

  • Not due to Nutritional deficiency
  • Growth Failure
  • May not respond to Arachitol injections
  • Repeated doses of Arachitol may contribute to to hypercalciuria & nephrocalcinosis
  • When to suspect non nutritional rickets

  • If child with Rickets shows
  • Failure to thrive
  • Dehydration
  • Constipation
  • Therapy resistance
  • Family History of rickets
  • Clinical Approach to child with non nutritional rickets

  • Proper History- polyuria, polydipsia, constipation, steatorrhea, drugs, FH
  • Check All records available of Weight, Height
  • H/O treatment taken so far including calcium supplements & Vit D taken in any form
  • Look for Acidotic breathing
  • Measure inter malleolar distance
  • Investigations

  • CBC
  • S.Ca/ PO4/ Alk Phos
  • S.Albumin/ SGPT
  • S.Creatinine
  • S.HCO3/ VBG
  • S.Electrolytes
  •  

     

    Rickets develops due to Lack of Vit D

  • Nutritional deficiency - Congenital Rickets
  • Malabsorption of fat soluble vitamins
  • DLiver disease or increased metabolism of Vit D due to anticonvulsants or other drugs
  • Chronic renal insufficiency
  • Vitamin D dependent rickets – genetic cause for deficiency of Active Vit D or end organ resistance to action of Active Vit D
  • Rickets also develops due to Phosphaturic states

  • Hypophosphatemic rickets - PHEX gene mutation. X linked disease The change created in the gene is a loss-of-function mutation and results in reduced breakdown of a substance known as fibroblast growth factor (FGF23). FGF23 acts on the kidney to cause increased phosphate excretion and decreased alpha-1 hydroxylase activity.
  • Oncogenic rickets - Secretion of FGF 23 by mesenchymal tumor
  • Renal Tubular Acidosis

  • Decreased renal synthesis of Active Vit D ,
  • Decreased Ca absorption, Hypocalcaemia,
  • Increased PTH which leads to phosphaturia & hypophosphatemia
  • Bone alkali mobilized to neutralize acids
  • Other possibilities

  • Hypophosphatasia Tissue non-specific alkaline phosphatase (TNSALP) deficiency in osteoblasts and chondrocytes impairs bone mineralization, leading to rickets or osteomalacia. The pathognomonic finding is subnormal serum activity of the TNSALP enzyme
  • Metaphyseal dysplasia It is characterized by defect in metaphyseal remodeling that leads to grossly widened metaphyses of long bones with marked cortical thinning and osteoporosis (Erlenmeyer-flask deformity) especially in the distal end of femur and proximal tibia.
  • Maccune Albright Syndrome - Polyostotic fibrous dysplasia , Cafe Au Lait Spots & Precocious puberty
  • Fluorosis
  • Nutritional Rickets

  • Common in Actively growing children
  • Their need is more :Active growth, Less supply of nutrients
  • No other systemic disease or dysfunction
  • Common problem in the community can be prevented by food fortification (milk)
  • Tests on Urine

  • Urine routine: PH, specific gravity, Pus cells
  • Urinary Na, K, Cl, HCO3
  • U.Calcium, PO4
  • U.Creatinine
  • Radiological investigations

  • X ray of Wrist/ Knee
  • X ray chest
  • USG Abdomen: Liver- Size, Echogenicity, fatty infiltration, KUB- stones, nephrocalcinosis
  • Lab Approach to a child with non nutritional rickets

  • Look at S.Calcium, PO4 & Alk phos
  • Confirm diagnosis of rickets
  • Look at SGPT, S.HCO3 & S.Creat
  • Whether liver disease, Acidosis &/Or renal failure
  • IF SGPT, S.HCO3 & S.Creat Normal
  • Possibility of Hypophosphatemia
    ( Low PO4, Normal S.Ca & PTH)
  • Vit D dependent rickets
    Low or normal PO4, Low S.Ca, High PTH)
  • Distal RTA suspected as

  • Failure to thrive
  • Hyperchloremic Normal anion gap Metabolic Acidosis
  • Positive urinary Anion Gap
  • Normal 25 OH Vit D level
  • Urinary bicarb undetected

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