Rickets biochemical

Bone scans were not performed, but typically in osteomalacia there is widespread under mineralization of osteoid, so unlike osteoporosis, osteomalacia is due to poor quality bone causing a loss of rigidity and strength, rather than a quantitative reduction ofbone. A condition in children, which is biochemically similar to osteomalacia, is rickets. Sufferers have misshapen bones of the head, spine and chest and typically bowed legs. 

On the basis of the concepts which we have developed, it appears most probable that, for various and diverse structural and biochemical reasons, the needs for vitamin D vary greatly from individual to individual. Children who are nonsusceptible to rickets require small amounts susceptible children require many times more children afflicted with vitamin D-resistant rickets require for a time, at least, extremely high doses. There are probably no sharp dividing lines between normals, susceptible individuals, and cases of vitamin D-resistant rickets. The susceptible individuals may make up an appreciable percentage of the population, for Park has found in postmortems on 230 children that about 46.5 per cent of children between 2 and 14 years have histological signs of rickets.41... 

The biochemical features of calcium-deficiency and vitamin D deficiency are very similar. Both disorders result in a low-to-normal serum calcium concentration, an elevated PTH level, a decreased or normal phosphorus concentration, and increased alkaline phosphatase activity. The serum concentration of 25-hydroxyvitamin D is normal or slightly decreased in calcium-deficiency rickets but is markedly decreased in vitamin D deficiency. On the other hand, the serum concentration of 1,25-dihydroxyvitamin D is greatly elevated in calcium-deficiency rickets but is normal or even slightly decreased in vitamin D-deficiency rickets. 

The fourth section deals with various aspects Digestion, Absorption, and Nutritional Biochemistry. The chapter Obesity considers current problems with respect to the ever-increasing incidence of imbalance between energy intake and utilization. Key problems of undemutrition are discussed in the chapters Protein-Energy Malnutrition and Vitamin A Deficiency in Children. The chapters Lactose Intolerance, Pancreatic Insufficiency, and Abetalipoproteinemia focus on the biochemical processes underlying food digestion and absorption. Calcium Deficiency Rickets, Vitamin B12 Deficiency, and Hemochromatosis provide discussions of absorption and utilization of vitamin D, vitamin B12, and iron, respectively. 

The disturbance of copper excretion, primarily due to a defect in the billiary excretion, is consistent with the biochemical findings in patients with Wilson disease. Urinary copper excretion is increased owing to total body overload of copper. Renal dysfunction includes albuminuria and renal rickets. Incorporation of copper in ceruloplasmin is impaired. Thus, there is a greater proportion of copper bound to albumin and amino acid complexes in the serum. But the overall copper concentration in serum is low. Ceruloplasmin is a multicopper oxidase see Copper Proteins Oxidases) that... 

Metabolic bone disease is a complication usually reported in adults and children receiving long-term home PN. This disorder in adults is characterized by osteomalacia with or without osteoporosis that may present without associated chnical, radiologic, or biochemical abnormalities. The diagnosis may not be made in premature infants until after the development of bone fractures or overt rickets. The etiology is poorly understood and likely multifactorial. Treatment options include pharmacologic intervention, calcimn and vitamin D supplementation, and exercise. Others have recommended removal of vitamin D from the PN in patients with low serum parathyroid hormone and 1,25-hydroxyvitamin D concentrations. ... 

Serum alkaline phosphatase elevation and other indices, both biochemical and radiological, of rickets and osteomalacia are more common in patients receiving anticonvulsant drugs than in control subjects (B13, C16, C37, R16, TIO). The severity of these abnormalities has been reported to relate directly to the duration of therapy (K35, TIO), to the... 

Svensson O, Engfeldt B, Reinholt FP, et al. 1987. Manganese rickets A biochemical and stereologic study with special reference to the effect of phosphate. Clin Orthop (No. 218) 302-311. 

K. Inouye (2001). Structure-function analysis of CYP27B1 and CYP27A1—Studies on mutants from patients with vitamin D-dependent rickets type I (VDDR-1) and cerebrotendinous xanthomatosis (CTX). Eur. J. Biochem. 268, 6607-6615. 

It is well known that vitamin D administration results in the alleviation of rickets and osteomalacia, or in biochemical terms stimulates the mineralization of organic matrix of bone and growth plate cartilage. The major defect in the mineralization of bone in vitamin D deficiency appears to be a lack of supply of calcium and phosphoras to the mineralization centers although a direct effect of some form of vita-... 

Our knowledge of the mode of action of vitamin D is incomplete, and no precise definition can be given in biochemical terms. It is clear that rickets, as commonly understood, results from a deficiency of vitamin D. The morphologist and the physiologist should have no real difficulty in agreeing that rickets is synonymous with the vitamin D deficiency syndrome, and that this term is intended to include all the primary and secondary effects. 

The question of vitamin supplementation obviously requires an affirmative answer when one considers therapy for overt, specific deficiency syndromes such as scurvy, rickets, beriberi, pellagra, megaloblastic anemia, ariboflavinosis, and convulsions due to pyridoxine deficiency. In some syndromes, biochemical evidence of deficiency occurring before overt symptoms is accepted as indication for general preventive supplementation. For example, the hydroxyphenyluria of premature infants and decreased serum phosphate and citrate, are taken as indications for early... 

The biochemical effects of the variants are reviewed in [2623, 2641]. Perhaps the most biologically plausible relationships of P450 27B1 variants are with rickets disease type I [2642] and fracture risk in the elderly [2643]. 

A disease resulting from a deficiency of one or more vitamins is hypovitaminosis (if vitamin is supplied in insufficient quantity) or avitaminosis (complete lack of vitamin manifested by some biochemical processes disorder). Deficiency of vitamins was formerly one of the main causes of many diseases and deaths. Pellagra (deficiency of some B-complex vitamins), scurvy (vitamin C), beriberi (thiamine), rickets (vitamin D), pernicious anaemia associated with reduced ability to absorb vitamin Bj2 (corrinoids) and xerophthalmia (vitamin A) are now well-known diseases caused by vitamin deficiency. Excessive intake of one or more vitamins (especially of lipophilic vitamins A and D) also causes an abnormal state resulting from disturbances of biochemical processes and can lead to severe diseases known as hypervitaminosis. 

The primary cause of rickets and osteomalacia is vitamin D deficiency and the clinical characteristics of these diseases depend on age at onset. The biochemical patterns of too low a serum concentration of 25(0H)D3, however, remain quite similar (Table 2) even though the structural effects on the skeleton differ. One common microscopic feature of the skeleton is that both rickets and osteomalacia... 

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