All about of Vitamin D , Rickets in child and Osteomalacia in adult .

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

Rickets

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

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Inappropriate calcium-phosphate

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homeostasis

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Defective bone mineralization

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Softening of the bones

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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 

Investigation

Xray show

•  widening,cupping and frying of metaphysis

•  wide gap between  epiphysis and metaphysis

• density of Shaft reduced

• Green stick fracture maybe present 

• rachitic rosary

• costrocondral 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

Treatment

Vitamin D3 suppliment,
Calcium supplementation, and
Phosphorus supplimentation.

Prevention

1.Exposure to sunlight
2.Vitamin D and calcium rich food intake
3.Regular vitamin D intake

Osteomalacia 

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.