Rickets and Vitamin D Flashcards
Epidemiology of Rickets?
25% in China
10% in Africa
Aetiology
- Vitamin D Disorders
- Nutritional deficiency
- Congenital deficiency
- Secondary deficiency (malabsorption, increased degradation, decreased liver 25-hydroxylase)
- Vitamin D dependent rickets type 1
- Vitamin D dependent rickets type 2
- CRF - Calcium deficiency
- Low intake (diet, prematurity)
- Malabsorption (primary disease, inhibitors of absorption) - Phosphorous deficiency
- Inadequate intake (premature)
- Aluminium containing antacids - Renal losses
- X-linked hypophosphatemic rickets
- AD hypophosphatemic rickets
- AR hypophosphatemic rickets
- Hereditary hypophosphatemic rickets with hypercalciuria
- Overproduction of phophatonin
- > Tumour induced, Mccune-Albright, Epidermal nevus, NF
- Fanconi syndrome
- Dent disease
- Distal RTA
Clinical features of Rickets?
General
- FTT, agitation, protruding abodmen, mm weakness, fractures
- Head
- Craniotabes, frontal bossing, delayed fontanelle closure, dental caries, craniosynostosis. - Chest
- Rachitic rosary, Harrison groove, resp infections and atelectasis. - Back
Scoliosis, kyphosis, lordosis. - Extremeties
- Enlargement of wrists and ankles, valgus/varus deformities, windswept deformities, anterior bowing, coxa vara, leg pain. - Symptomatic hypocalcemia.
- Tetany, seizures, stridor from laryngeal spasm.
In Vitamin D deficiency, what would you expect levels of the following to be?
Ca, PO4, PTH, 25OHD, 1,25 OHD, ALP, Urine Ca, Urine PO4
Ca - normal or low PO4 - decreased PTH - Increased 25 OHD - Decreased 1,25 OHD - Decreased, normal or increased ALP - increased Urine Ca - decreased Urine PO4 - increased
In VDDR 1, what would you expect levels of the following to be?
Ca, PO4, PTH, 25OHD, 1,25 OHD, ALP, Urine Ca, Urine PO4
Ca - normal or low PO4 - decreased PTH - increased 25 OHD - normal 1,25 OHD - decreased ALP - increased Urine Ca - decreased Urine PO4 - increased
In VDDR 2, what would you expect levels of the following to be?
Ca, PO4, PTH, 25OHD, 1,25 OHD, ALP, Urine Ca, Urine PO4
Ca - normal or low PO4 - low PTH - high 25 OHD - normal 1,25 OHD - increased markedly ALP - increased Urine Ca - decreased Urine PO4 - increased
In Chronic renal failure , what would you expect levels of the following to be?
Ca, PO4, PTH, 25OHD, 1,25 OHD, ALP, Urine Ca, Urine PO4
Ca - normal or low PO4 - high PTH - high 25 OHD - normal 1,25 OHD - decreased ALP - increased Urine Ca - normal or decreased Urine PO4 - decreased
In dietary PO4 deficiency, what would you expect levels of the following to be?
Ca, PO4, PTH, 25OHD, 1,25 OHD, ALP, Urine Ca, Urine PO4
Ca - normal PO4 - low PTH - normal or low 25 OHD - normal 1,25 OHD - high ALP - high Urine Ca - high Urine PO4 - low
When can you get dietary PO4 deficiency
Almost never. Only when you use antacids +++.
What’s the difference between VDDR type 1 and type 2?
VDDR type 1 is problem with 1 alpha hydroxylase.
- AR.
- Present in first 2 years of life.
- Can also cause metabolic acidosis and aminoaciduria.
- treat with calcitriol to maintain low normal Ca, high PTH.
VDDR type 2 is problem with Vit D receptor.
- AR. Occurs in infancy
- 50-70% have alopecia.
- some patients respond to high dose Vit D2, 25 D or 1-25 D
In X linked hypophosphataemic rickets, what would you expect levels of the following to be?
Ca, PO4, PTH, 25OHD, 1,25 OHD, ALP, Urine Ca, Urine PO4
Ca normal PO4 low PTH -normal 25 OHD - normal 1,25 OHD - relatively reduced ALP - high Urine Ca - low urine PO4 - high
What is X-linked hypophosphatemic rickets?
X-linked dominant condition
Defective PHEX gene (PHosphate regulating gene with homology to Endopeptidases on the X chromosome.
Product of htis gene have indirect role in inactivating phosphatonin FGF-23. Mutations lead to increase FGF-23 (inhibit phosphate reabsorption in proximal tubule, also inhibits 1alpha hydroxylase). Clinical feature: Lower extremity abnormalities Poor growth Delayed dentition and teeth abscess
