Page 235 - Concise Pathology for Exam Preparation ( PDFDrive )

220 SECTION I General Pathology

Q. Enumerate the factors that predispose to rickets and osteomalacia.

Ans. Factors predisposing to rickets and osteomalacia are
• Inadequate synthesis or dietary deficiency of vitamin D
• Inadequate exposure to sunlight
• Limited dietary intake of fortified foods
• Poor maternal nutrition during pregnancy and breastfeeding
• Decreased absorption of vitamin D (fat-soluble vitamin)
• Cholestatic liver disease
• Biliary tract obstruction
• Pancreatic insufficiency
• Diseases of small intestine
• Deranged vitamin D metabolism
• Impaired synthesis of 25-hydroxy vitamin D
• Increased degradation of vitamin D and 25-hydroxy vitamin D
• Decreased synthesis of 1,25-dihydroxy vitamin D
• Resistance to action of 1,25-dihydroxy vitamin D

Q. Enlist the manifestations of vitamin D deficiency.
Ans. The following are the salient features of vitamin D deficiency:
• The most common cause is inadequate exposure to sunlight. Thus, vitamin D deficiency
occurs mainly among people who do not spend much time outdoors.
• Because breast milk contains only small amounts of vitamin D, breastfed infants are at
risk of rickets.
• In malabsorption disorders, patients cannot absorb vitamin D because it is a fat-soluble
vitamin, which is normally absorbed with fats in the small intestine.
• The body may not be able to convert vitamin D to an active form. Certain kidney and
liver disorders and several rare hereditary disorders interfere with this conversion, as do
certain drugs, such as some anticonvulsants and rifampin.

Manifestations of Vitamin D Deficiency
• Manifests with rickets in children and osteomalacia in adults.
• In young infants who have rickets, the entire skull may be soft. Older infants may be
slow to sit and crawl, and the spaces between the skull bones (fontanelles) may be slow
to close.
• In children aged 1–4 years, bone growth may be abnormal, causing an abnormal curve
in the spine and bow legs or knock-knees. These children may be slow to walk.
• For older children and adolescents, walking is painful. The pelvic bones may flatten,
narrowing the birth canal in adolescent girls.
• Deformities of skeleton like craniotabes (parietal bones buckle inwards by pressure;
with the release of pressure, elastic recoil snaps the bone back into its original posi-
tion), frontal bossing, squared appearance of frontal head (due to excess of oste-
oid), rachitic rosary (overgrowth of cartilage or osteoid tissue at the costochondral
junction), pigeon chest deformity (weakened metaphyseal areas of the ribs are sub-
ject to the pull of respiratory muscles and thus bend inward, creating anterior protru-
sion of the sternum) and Harrison groove (created by the inward pull at the margin
of the diaphragm) are also seen.
• In adults, the spine is affected (lumbar lordosis), pelvis and leg bones weaken. Affected
areas may be painful to touch, and fractures may occur.

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