Rickets Flashcards
(11 cards)
What is rickets?
Defective bone mineralisation causing ‘soft’ and deformed bones.
Same as osteomalacia in adults.
What are the causes of rickets?
Deficiency in vitamin D or calcium.
What are the risk factors for rickets?
Darker skin, low exposure to sunlight, colder climates, a lot of time indoors, prolonged breastfeeding.
What is a rare form of rickets called?
Hereditary hypophosphataemic rickets is a rare form caused by genetic defects that result in low phosphate in the blood.
The most common form is x-linked dominant, but it also has other modes of inheritance.
What is the pathophysiology of rickets?
- vitamin D is a hormone created from cholesterol by the skin in response to UV radiation
- reduced sun exposure without vitamin D supplementation leads to vitamin D deficiency
- patients with malabsorption disorders (eg. IBD), are more likely to have vitamin D deficiency
- they kidneys are essential in metabolising vitamin D to its active form, therefore vitamin D deficiency is common in CKD
- vitamin D is essential in calcium and phosphate absorption from the intestines and kidneys
- vitamin D is also responsible for regulating bone turnover and promoting bone reabsorption to boost the serum calcium level
- inadequate vitamin D leads to a lack of calcium and phosphate in the blood
- as calcium and phosphate are required for the construction of bone, low levels result in defective bone mineralisation
- low calcium causes a secondary hyperparathyroidism as the parathyroid gland tries to raise the calcium level by secreting parathyroid hormone
- PTH stimulates increased reabsorption of calcium from the bones
- this causes further problems with bone mineralisation
What are the presentations of rickets?
- vitamin D and rickets patients may not have any symptoms
- lethargy
- bone pain
- swollen wrists
- bone deformity
- poor growth
- dental problems
- muscle weakness
- pathological or abnormal fractures
What bone deformities can occur in rickets?
- bowing of the legs, where the legs curve outwards
- knock knees, where the legs curve inwards
- rachitic rosary, where the end of the ribs expand at the costochondral junctions causing lumps along the chest
- craniotabes, which is a soft skull, with delayed closure of the sutures and frontal bossing
- delayed teething with under development of the enamel
What investigations are needed for rickets?
- serum 25-hydroxyvitamin D is the lab investigation for vitamin D → less that 25nmol/L established a diagnosis of vitamin D deficiency ⇒ rickets
- x-ray needed to diagnose rickets → it may also show osteopenia (more radiolucent bones)
- serum calcium may be low
- serum phosphate may be low
- serum alkaline phosphatase may be high
- PTH may be high
What additional investigations should be done to look for other pathologies?
- FBC and ferritin for iron deficiency anaemia
- inflammatory markers eg. ESR and CRP for inflammatory conditions
- kidney function tests for kidney disease
- LFTs for liver pathology
- malabsorption screen eg. anti-TTG antibodies for coeliac disease
- autoimmune and rheumatoid tests for inflammatory autoimmune conditions
What should breastfeeding women take?
- breastfed babies are at a higher risk of vitamin D deficiency compared with formula fed babies, as formula feed is fortified with vitamin D
- breastfeeding women and all children should take a vitamin D supplement → supplements containing 400 IU (10 micrograms) per day for children and young people
How can children with vitamin D deficiency be treated?
- with vitamin D (ergocalciferol)
- the doses for treatment of vitamin D deficiency depend on the age
- the dose for children between 6 months and 12 years is 6000 IU per day for 8-12 weeks
- children with features of rickets should be referred to a paediatrician
- vitamin D and calcium supplementation is used to treat rickets
