Sources of Vitamin D
★Endogenous synthesis from skin(that’s why its called a hormone due to synthesise in the body)
★Food rich in vitamin D (egg yolk,cod liver oil,butter, any fat rich diet)
Function and metabolism
Vitamin D maintain serum calcium and phosphorus concentration that supports cellular processes, neuromuscular function and bone mineralization . Vitamin D does this by:
- increasing calcium absorption from intestine( duodenum maunly)
- Stimulation of calcium reabsorption from kidney(Distal renal tubules)
- Act on parathormone to control serum calcium concentration.
Vitamin D disorders
Deficiency of vitamin D in growing children occrs due to imperfection of mineralization of bones and softening and destruction of the bones
Aetiology of vitmin D
- Prolong non exposure to sunlight
- Food deficient in vitamin D
- Kidney diseases( chronic kidney disease, renal tubular acidosis)
- Genetic disorders ( familial hypophosphatemic rickets, fancony syndrome, cystinosis)
- Malabsorption of vitamin D( liver and intestinal disorders)
Pathogenesis of rickets
Lack of Vitamin D
Defective bone mineralization
Softening of the bones
Deformities and short stature
- Short stature
- protruded abdomen
- muscle weekness
- Box like head
- Delayed dentation
- dental carries
- poor enamel formation
- Pigeon chest deformities
- Harrison sulcus
- rachitic rosary
- Widening of wrist and ankle
- coxa vara and vulgus
- anterior bowing of leg
- gait deformities
- stridor due to laryngeal spasm
- Scoliosis and
widening,cupping and frying of metaphysis wide gap between epiphysis and metaphysisdensity of Shaft reducedGreen stick fracture maybe present rachitic rosarycostrocondral ends of ribs ar expanded, cupped and indistinct
- Serum calcium (sc): usually normal
- Serum phosphorus (sp): low
Rachitic index( SC*SP)
Less than 30 :rickets likely
More than 40 :rickets unlikely
In between30-40 : doubtful
- Serum ALP: high
Serum PTH: high
Serum 25 (OH)D and 1,25 (OH)2D: low
Serum creatinine: high in CKD and RTA
Serum electrolyte: altered in CKD and RTA
- Urine for glucose : glycosuria(glucose present in urine)
- Urine for amino acid : aminoaciduria(amino acid present in urine) in fancony syndrome
- 24hour urinary calcium concentration: high in fancony syndrome
- Twenty four hour urinary phosphate concentration: high in RTA(road traffic accident) , X linked hypophosphatemic rickets and fancony syndrome, etc
Vitamin D3 suppliment,
Calcium supplementation, and
1.Exposure to sunlight
2.Vitamin D and calcium rich food intake
3.Regular vitamin D intake
Deficiency of Vitamin D is the most common cause of osteomalacia in Adult. Vitamin D is an important nutrient that helps us absorb calcium ion in our intestine.
Certain conditions can interfere with the absorption of vitamin D and lead to Osteomalacia :
- Celiac disease an damage the lining epithelium of our intestines and prevent the absorption of many nutrients like vitamin D.
- cancer( some types) can interfere with vitamin D processing.
- Liver and kidney disease can affect the metabolism of vitamin D.
- A diet that doesn’t include phosphates can cause phosphate lower , which can lead to osteomalacia.
- Drugs induced osteomalacia: phenoytin phenobarbital etc
Sign and symptoms
- Bones fracture easily.
- muscle weakness
- hard time walking
- may develop a waddling gait.
- Bone pain, especially in hips, is also a common symptom.
- A dull, aching pain can spread from our hips to the lower back, pelvis, legs and ribs
very low levels of calcium in blood may causes :
- Arrhythmia or irregular heart beat
- Tingling and numbnes around the mouth and
- Tingling and numbness in the hands and feets.
- Spasms in hands and feets
Diagnosis of Osteomalacia :
- low levels of vitamin D
- low levels of calcium
- low levels of phosphorus
- Alkaline phosphatase is high (indicate Osteomalacia)
- Parathyroid hormone high (suggest lack of vitamin D)
- X ray show small cracks in bones(these cracks are called looser’s transformation zones. Fracture begin with this zone
Treatments of Osteomalacia :
- oral supplements of vitamin D, calcium, or phosphate for early detection
- Exposure to sunlight for Vitamin D production.
- Liver and kidney disease treatment prevent Osteomalacia due to liver and kidney disease can cause impairment of Vitamin D production.