Malnutrition in a child: Rickets Flashcards
Define rickets.
A disorder of the growing skeleton due to inadequate mineralisation of bone as it is laid down at the epiphyseal growth plates. There is characteristic widening of the ends of the long bones and characteristic radiology. Osteomalacia occurs when there is inadequate mineralisation of mature bone. Both rickets and osteomalacia may be present at the same time.
Explain the aetiology/risk factors of calcium deficiency in rickets.
Dietary, malabsorption
Explain the aetiology/risk factors of Vitamin D deficiency in rickets.
Vitamin D deficiency: Dietary, malabsorption, lack of sunlight, iatrogenic (drug-induced, e.g. phenytoin therapy).
Defect in vitamin D metabolism: Vitamin D-dependent rickets type 1 (1 alpha hydroxylase deficiency); liver disease, renal disease.
Defect in vitamin D action: Vitamin D-dependent rickets type II- autosomal recessive condition. Due to mutations in the Vitamin D receptor gene, leading to end-organ resistance to vitamin D.
Explain the aetiology/risk factors for phosphate deficiency in rickets.
Renal tubular phosphate loss (isolated): hypophosphataemic rickets:
- X-linked
- Autosomal recessive
- Autosomal dominant
Acquried hypophosphataemic rickets:
- Fanconi syndrome
- Renal tubular acidosis
- Nephroxic drugs
Reduced phosphate intake
What are the three characteristic stages of rickets?
- Stage 1: Low plasma calcium/normal plasma phosphate
- Stage 2: Normal plasma calcium (restored due to compensatory hyperparathyroidism)
- Stage 3: Low plasma calcium and phosphate- advanced bone disease
Stages 1 and 2 are biochemically evident only. Stage 3 has clinical features.
Summarise the epidemiology of rickets.
The peak prevalence of vitamin D-deficient rickets is characteristically between 6 and 18 months of age, with a further smaller peak occurring during adolescence.
Globally, nutritional deficiencies are the leading cause of rickets, followed by vitamin D-dependent, vitamin D-resistant, and renal rickets.
What are the signs and symptoms of rickets?
Growth delay or arrest
Bone pain fracture
Muscle weakness
Skeletal deformities:
- Swelling of wrists
- Swelling of costrochondral junctions (‘rickety rosary’)
- Bowing of the long bones
- Frontal cranial bossing
- Craniotabes (softening of skull)
What are appropriate investigations for rickets?
Radiological: X-ray of wrists (generalized osteopenia/widening, cupping and fraying of metaphyses)
What is the management for rickets?
Prevention: In the UK all infants should receive vitamin D daily ((280–340 IU, multivitamin or fortified infant formula) and pregnant/lactating mothers should receive 400 IU daily.
Dietary vitamin D sources: Fatty fish (herring, mackerel, sardines, tuna, salmon), egg yolk, fortified foods (infant formula, shop-bought milk, breakfast cereal, margarine).
Supplementation for vitamin D deficiency: Ergocalciferol (vitamin D2) or cholecalciferol (vitamin D3) is indicated in nutritional vitamin D deficiency. Alfacalcidol should only be used if there is severe liver or renal disease. Oral calcium supplements are usually required initially if the child is hypocalcaemic and/or dietary intake is poor. Serial bloods should be measured. Treatment usually lasts 2–4 months.
What are complications are associated with rickets?
Rickets. Low maternal vitamin D may adversely affect the developing fetal brain and has been shown to affect postnatal head and linear growth.
What is the prognosis of rickets?
Bony abnormalities may take up to 2 years to resolve after treatment has been administered.
