Rickets

 

 

Rickets is defined as failure of mineralization of the growing bones, which should not be confused with osteomalacia i.e. defective mineralization of mature bones, or osteoporosis i.e. demineralization of pre-mineralized bones.

Rickets may be broadly divided into two categories Vitamin D deficiency or nutritional rickets, and Vitamin D-resistant or refractory rickets. Nutritional rickets accounts for over 90% cases in childhood.

Vitamin D at glance

RDA: 200 IU/day

Clinical manifestations

Rickets commonly present at 6 months – 2 years of age with bony deformities and hypotonia of supporting ligaments/muscles. Important changes in Rickets are –

Craniofacial changes:

Craniotabes –  softening and thinning of skull bones with pin-pong ball like resilience on pressure over parietal bones (normal <3 months).

Frontal bossing – prominence of frontal bones

Caput quadratum – Box-head or hot crass-bun appearance due to fronto-panetal bossing,

Delayed closure of anterior fontanel,

Delayed dentition.

Thoracic changes:

Rachitic rosary – round, non-tender beading due to widening of costochondral junctions,

Harrison sulcus – a groove/depression along the lower costal margins,

Sternal deformities like Pectus excavatum i.e. depression of sternum, Pectus carinatuin i.e. forward projection of sternum, or pigeon-chest deform it

Limb deformities:

Widening of wrist/ankles (double malleolus) due to widened epiphysis and metaphysic,

Gait abnormalities e.g. Knockknee (Genu incurvatum), Bowlegs and Coxa-vera,

Green-stick pathological fractures of long bones.

Spinal deformities:

Kyphosis or scoliosis due to lax ligaments,

Short stature due to deformed spinal curvature.

Generalized hypotonia with –

Pot-belly, due to abdominal muscle hypotonia,

Visceroptosis due to ligamental laxity,

Hyper-extensible joints (acrobatic rickets).

Other manifestations e.g. excessive sweating over forehead, recurrent respiratory infections etc.

Rickets in severely malnourished children may present without clinical signs despite extensive radiological changes (atrophic rickets).

Diagnosis of rickets

Typical clinical deformities, discussed above,

Characteristic radiological changes, best demonstrated at wrist joint, shoving –

Widening of epiphyseal ends with increased space between diaphysis and epiphysis, due to poor visibility of thickened but uncalcified metaphysis.

Fraying at the visible end of long bones, (raveled sleeve appearance), due to irregular mineralization of metaphysis.

Cupping i.e. concavity at the visible end of long bones, due to poor mineralization of relatively less vascular center and pressure changes

Splaying of the ends off long bones, due to pressure changes on poorly mineralized bones

Other late changes include delayed bone age, costochondral widening with spatulate ribs, tn-radiate pelvis and spinal defonnities.

After Vitamin D administration, radiological recovery is visible in 7-10 days with appearance of provisional zone of preparatory calcification – a transverse line beyond the visible end of shaft, suggestive of healing rickets. Absence of this zone till 3 weeks indicates possibility of refractory rickets. Complete X-ray clearance takes 2-3 months, though deformities may persist for many years.

Prevention of rickets involves adequate exposure to sunlight and Vitamin D supplement (P0 4001U/day) in preterms or rapidly-growing children.

VITAMIN D RESISTANT Rickets

Vitamin D resistant rickets are less common but important indicators of many systemic or metabolic defects. Some important causes of resistant rickets are as follows –

Familial gypophosphatemia, an X-linked dominant disease, is a leading cause of non-nutritional rickets due to defects in – a ) renal reabsorption of phosphates, with consequent phosphaturia and hypophosphatemia, b) conversion 0f 25(OH) D3 into 1,25(OH)2D3.

Clinically, these cases usually present as toddlers with severe bow-legs and waddling gait, typically more severe in males.

Diagnosis rests on – a) no responses to Vitamin D therapy, b) similar family history c) heavy phosphaturia. Despite hypophosphatemia, and d) absence of glucosuria, aminoaciduria and bicarbonaturia (did Renal tubular acidosis).

Treatment includes daily phosphate supplements as Joulie solution (P0 0.5-1.0 gm/d q4hr), along with Vitamin D2 (2000 IL Tikgid) or preferably, 1,25 (OH) 2D3 (50-60 ngikgid). Mega Vitamin D therapy, as used in nutritional rickets, should be avoided due to the risk of hypercemia and nephrocalcinosis.

Vitamin D-Dependent rickets manifest at 3-6 months of age and are of two types –

Type I, due to 25(OH) D3 -1ct-hydroxylase deficiency that prevents renal conversion of Vitamin D into active form, and

Type II, due to inherited end-organ resistance.

While type I may be treated with massive doses of Vitamin D7 (2-10 lac IU/day), type II needs to be treated with 1,25(OH)2D3 (15-30 jag/Kg/day).

Thanks,

Health, August- 2012