Vitamin D-Deficiency Rickets - Where Do We Stand?


Austin J Pediatr. 2014;1(1): 1001.

Vitamin D-Deficiency Rickets - Where Do We Stand?

Milan Bayer*

Department of Pediatrics, Charles University in Prague, Faculty of Medicine in Hradec Králové, University Hospital Hradec Králové, Czech republic

*Corresponding author: Milan Bayer, Departmentc of Pediatrics, Charles University in Prague, Faculty of Medicine in Hradec Králové, University Hospital Hradec Králové, Czech Republic

Received: March 20, 2014; Accepted: April 06, 2014; Published: April 08, 2014

Vitamin D–binding protein belongs to prime albuminoidal proteins. It was documented that vitamin D was produced by ultraviolet (UV) irradiated phytoplankton and zooplankton already 500 million years ago. Vitamin D– receptor (VDR) has been detected in a wide range of primitive animals. In biological studies lamprey, zebra fish, frog, mouse, and human VDR´s were found to have similar ligand selectivity’s for vitamin D derivatives. Original role of active vitamin D (1alpha, 25–dihydroxyvitamin D3; calcitriol) was protective and immunological. VDR sensitivity to hepatotoxic secondary bile acids facilitated expression of cytochrom P450 enzymes detoxifying these acids in the liver and intestine. When animals left seas and colonized earth, the maintenance of strict mineral homeostasis became very important survival condition. At that time vitamin D and VDR involved in mineral metabolism. It is now evident that in human calcium absorption is highly vitamin D dependent during infancy until the end of puberty.

More than 90% of necessary vitamin D is formed in the skin from 7–dehydrocholesterol under the influence of UV light type B. During the winter, vitamin D composition in the skin is very low below 40 degrees and above 40 degrees. Line of latitude due to unfavorable sun location over the horizon in part of the year. It means that from May to September (southern hemisphere) and from October to April (northern hemisphere) UV exposition of skin in those areas is too low to cover common vitamin D requirements. Predecessors of human being lived in the middle Africa. The migration of populations out of the tropics consequently resulted in selective pressures favoring lighter skin in order to facilitate coetaneous previtamin D3 biosynthesis in regions far from the equator, under low UVB radiation. Four genes associated with this trait in Europeans were recently documented – KITLG, TYRP1, SLC24A5, and SLC45A2. The onset of the sweep shared by Europeans and East Asians at KITLG occurred about 30,000 years ago and the selective sweeps for the European–specific alleles at TYRP1, SLC24A5, and SLC45A2 started within the last 11,000–19,000 years. During the last ten thousand years none significant change in our genome appeared. But human populations went through large changes in their life style, especially in last several centuries.

Bone deformities in children corresponding to rickets were for the first time reported by roman physician Sopranos in 2nd century. Medical student David Whistler published his paper “De morbo puerileanglorum, quem patrio idiomatic indigene vacant the Rickets” in 1645. He presumed influence of alcohol during pregnancy in etiology of this illness. But only Francis Gilson’s description of rickets from 1650 is considered as official. He provided more detailed observation, recognized rickets as noninfectious disease and denatured it from scurvy. It was industry development with increasing air pollution in industrial areas, and child labor with their undernourishment and low exposition to UVB radiation which contributed to pathologists´ observation in second half of 19th century when some sign of rickets could be seen in 80–90% anatomized children. In 1920´s, studies in lion cubs, dogs, and rats showed the importance of cod liver oil in therapy of nutritional rickets. New anthracitic substance later termed vitamin D was described and distinguished from vitamin A. The efficacy of UV irradiation in prevention and treatment of rickets was established. Nevertheless, there were documented next to 14.000 deaths from rickets in The United States in period 1910–1961 and in 1940´s, rickets was still regarded as �probably the most common disease of early childhood.

Rickets is a disease characterized with insufficient and delayed mineralization of endochondral bone formation at the growth plates. Repeated decrease of calcemia results in secondary hyperparathyroidism. The main consequences of this situation are hyperphosphaturia, and stimulation of 1–alpha hydroxylase activity leading to increase of calcitriol levels, followed by bone tissue degradation and bone cells activity. Clinical manifestation as well as typical X–ray picture (Figure 1) of rickets on long bones appears. In case of untreated patient the 25–hydroxyvitamin D is run out and absolute or relative calcitriol deficiency appears. Calcium mobilization from bone becomes insufficient and hypocalcaemia and hypophosphatemia is going along with the effects of secondaryhyperparathyroidism in severe apparent rickets.

Citation: Bayer M. Vitamin D-Deficiency Rickets - Where Do We Stand?. Austin J Pediatr. 2014;1(1): 1001. ISSN: 2381-8999