CDS (I) 2022 General Knowledge · Question 18 of 120

Correct — B, Vitamin D. Rickets is the childhood bone disease that follows a shortage of vitamin D, and it usually appears between about three and eighteen months of age. The mechanism runs through calcium: vitamin D is what allows calcium to be absorbed from food in the gut, so without it the blood calcium falls and the growing bone never mineralises properly. Soft bone under a child's own weight gives the classic signs — bowed legs, thickened wrists and ankles, a large forehead, bone pain and stunted growth. The same deficiency in an adult, whose bones have stopped growing, produces osteomalacia instead. Sunlight matters because skin makes vitamin D when ultraviolet light reaches it, which is why the disease is associated with too little sun as much as with too little in the diet.

• (a)Vitamin C — A shortage of vitamin C gives scurvy — bleeding gums, poor wound healing and weakness — because vitamin C is needed to make collagen. It affects connective tissue rather than the mineralisation of bone.
• (c)Vitamin A — Vitamin A deficiency shows up in the eye first, as night blindness and, if it goes on, as xerophthalmia and damage to the cornea. It is a leading preventable cause of childhood blindness, but it does not bend the legs.
• (d)Vitamin B — The B group covers several vitamins with several deficiency diseases — beriberi from B1, pellagra from B3, anaemia from B12 — and none of them is rickets. The option is also the vaguest of the four, since 'Vitamin B' names a family rather than a substance.

Vitamins are organic substances needed in small amounts that the body cannot make in sufficient quantity for itself, so each has a characteristic deficiency disease. The fat-soluble group — A, D, E and K — is stored in the body, while the water-soluble group — the B vitamins and C — is not, and has to be supplied regularly. Vitamin D is unusual in being partly self-supplied: ultraviolet light acting on the skin converts a precursor into the vitamin, and only the shortfall has to come from food. Its dietary sources are oily fish, cod liver oil, egg yolk, liver and fortified milk.

Deficiency diseases are best learnt as a paired list rather than one at a time, because examiners set them against each other. Vitamin A goes with night blindness, B1 with beriberi, B3 with pellagra, B12 with pernicious anaemia, C with scurvy, D with rickets in children and osteomalacia in adults, and K with poor blood clotting. Rickets is worth a second look because it is the one whose cause is not purely dietary — a child eating adequately but kept out of sunlight can still develop it, and vitamin D deficiency remains common in India despite the abundant sunshine, since clothing, indoor living and skin pigmentation all reduce how much is made.

• Rickets is caused by vitamin D deficiency and typically begins between three and eighteen months of age.
• Vitamin D is needed for calcium to be absorbed from food; without it blood calcium falls and bone fails to mineralise.
• Its signs are bowed legs, thickened wrists and ankles, a large forehead, bone pain and stunted growth.
• The equivalent disease in adults is osteomalacia; the bones are already grown, so they soften rather than deform in growth.
• Ultraviolet light on the skin converts a precursor into vitamin D, which is why sunlight exposure matters alongside diet.

• Swapping rickets and scurvy, the two most often confused deficiency diseases.
• Assuming a deficiency disease must come from diet alone, when vitamin D also depends on sunlight.
• Treating 'vitamin B' as a single substance rather than a family with several separate deficiency diseases.

As a straight vitamin-to-disease pairing, or as a match list in which three or four such pairs have to be checked at once.

• practice — not a real PYQ

  The adult counterpart of rickets, in which already-formed bone softens rather than deforming during growth, is

  • (a)osteoporosis
  • (b)osteomalacia
  • (c)arthritis
  • (d)scurvy

  Answer(b) osteomalacia — the same vitamin D deficiency acting on a skeleton that has already finished growing.

• practice — not a real PYQ

  Which one of the following pairs is correctly matched?

  • (a)Vitamin A — scurvy
  • (b)Vitamin B1 — night blindness
  • (c)Vitamin C — beriberi
  • (d)Vitamin K — poor blood clotting

  Answer(d) Vitamin K — poor blood clotting. Scurvy belongs to vitamin C, night blindness to vitamin A and beriberi to vitamin B1.