Vitamin  D

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

Inappropriate calcium-phosphate


Defective bone mineralization

Softening of the bones

Deformities and short stature

Clinical features

  • 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 
  • Tetany
  • stridor due to laryngeal spasm
  • Seizure
  • Lordosis
  • Scoliosis and 
  • Kyphosis 
Normal bones vs rockets disease bones


Xray show

 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

Blood picture

  • 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 picture

  1. Urine  for glucose : glycosuria(glucose present in urine)
  2. Urine for amino acid : aminoaciduria(amino acid present in urine) in fancony syndrome
  3. 24hour urinary calcium concentration: high in fancony syndrome
  4. 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
Phosphorus supplimentation.


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. 
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