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Saudi Journal of Kidney Diseases and Transplantation
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CASE REPORT Table of Contents   
Year : 2010  |  Volume : 21  |  Issue : 1  |  Page : 128-130
Familial vitamin D deficient osteomalacia and renal osteodystrophy: Shaping up the debate


New Medical Center Specialty Hospital, Dubai, United Arab Emirates

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Date of Web Publication8-Jan-2010
 

   Abstract 

Osteomalacia is a common occurrence world over due to the deficiency in vitamin D and calcium intake. We present here two sisters with features of sever osteomalacia, myopathy and hypophosphatemia hyperparathryroidism and 25(OH)D2, 25(OH)D3and 1,25(OH)D3 levels were very low.

How to cite this article:
Jabur WL. Familial vitamin D deficient osteomalacia and renal osteodystrophy: Shaping up the debate. Saudi J Kidney Dis Transpl 2010;21:128-30

How to cite this URL:
Jabur WL. Familial vitamin D deficient osteomalacia and renal osteodystrophy: Shaping up the debate. Saudi J Kidney Dis Transpl [serial online] 2010 [cited 2014 Oct 23];21:128-30. Available from: http://www.sjkdt.org/text.asp?2010/21/1/128/58787

   Introduction Top


It is rarely reported nowadays the severe skeletal manifestations of osteomalacia secon­dary to vitamin D deficiency, especially among young females, of Arabic descent who are wor­king outdoor and residing in the Persian gulf region where a hot sunny climate prevails around the year. The main risk factors are usually dark skin and intake of vegetarian diet. Similarly the renal osteodystrophy related to vitamin D deficiency is often encountered and has still debatable etiology. By reporting these patients we are trying to discover the probable etiology and the pathological mechanisms un­derlying osteomalacia and renal osteodystrophy.


   Case History Top


Two sisters 29and 28 years old from Arabic descent were referred from the neurology cli­nic for further management. Their main com­plaint was lower limb proximal muscle wea k­ness that had progressed in severity over the last two years. A primary diagnosis of proxi­mal myopathy was made. Both had dark skin with remarkable history of bilateral lower limb proximal muscular weakness. Electromyogra­phic and nerve conduction studies revealed myopathic changes. Radiological examination of the pelvis and lower limb showed genera­lized osteopenia, multiple collapsed fractures of the vertebrae, and loosers zone in the proxi­mal femure. Other investigations showed bor­derline serum calcium and phosphorus, remar­kably elevated bone alkaline phosphatase, 24­hour urinary excretion of calcium and phos­phorus were very low, parathyroid hormone was dramatically elevated, and 25(OH)D2, 25 (OH)D3 and 1,25(OH)D3 levels were very low. Antigliadin antibodies were negative. Renal and hepatic functions were normal. They also had iron deficiency anemia. A primary diagno­sis of osteomalacia was made and treatment with vitamin D in the form of 25(OH)D2 and calcium was commenced.


   Discussion Top


Its obvious that the osteomalacia is secondary to vitamin D deficiency which is reflected by very low serum 25(OH)D2 < 10 nmol/L (normal range 75-200) and low 1, 25(OH)D3 23 pmol/L (normal range 43-140). The increased parathy­roid hormone tries to maintain serum calcium within normal limits by sacrificing the bone matrix, however to a marginal degree in our patients (serum calcium is 8.3and low urinary calcium and phosphorus excretion). This high­lights the pivotal role of vitamin D in calcium and phosphorus homeostasis.

We are reporting this case for several rea­sons. Being familial is an unusual feature for osteomalacia secondary to vitamin D deficiency. The drastically low 25(OH)D (severe vitamin D deficiency defined as serum 25(OH)D be­low 20 nmol/L) and the severity of the disease are unexpectedly out of proportion to the cur­rently reported tempo of the disease in general. The mutual presentation of osteomalacia in both of the sisters as a myopathic syndrome is unusual. Whether the patients are having unique inherent predisposition to develop myopathy or it's a presentation of vitamin D deficiency, needs further clarification. Pure vegetarian diet was the only risk factor; nevertheless such diet causing an advanced osteomalacia is difficult to explain solely.

Proximal myopathy has been reported in osteo­malacia [1] , however the debate remains that is it the hypovitaminosis D, hypocalcemia, hypo­phosphatemia, or the secondary hyperparathy­roidism is the culprit. It is understandable that deficiency of 1,25(OH)2D in renal failure pa­tients is parallel to the decline in renal func­tion, nevertheless the presence of deficiency of the 25(OH)D which is usually severe and also widely recognized in such patients is more than expected. [2] One probable theoretical rea­son that needs further exploration is the ac­quired enzymatic defect in the pathway of 25 (OH) vitamin D synthesis . On the other hand, living in the gulf region would abrogate the supposition of under exposure to the ultra violet light which is commonly encountered in the northern latitude. [3] The first contrasting feature to nonuremic osteomalacia is the promi­nent hypocalcimea despite the presence of a recognizable secondary hyperparathyroidism early in the disease process. This might be ex­plained either by poor responsiveness of bone to higher level of parathyroid hormone or by the fact that the fraction of ionized calcium is raised by the acidic milieu causing negative feed back the parathyroid gland. [4] Proximal myopathy is not a common presentation in ure­mic patients nevertheless, there are several con­founding factors to cause the muscle disease in chronic renal failure. [4] The second significant outstanding variance from non-uremic osteoma­lacia is the hyperphosphatemia which incurred despite the prominent deficiency of 1, 25(OH) 2D3 and the secondary hyperparathyroidism that are encountered at earlier stages in the chro­nic renal failure. Hyperphosphatemia is direct­ly related to the decline in GFR [5] contrary to our patients where etiology of hypophosphate­mia was not related to increased urinary ex­cretion due to secondary hyperparathyroidism causing hyperphosphaturia. [6] Thereupon three intriguing inquiries we have to emphasize on, first; is there any genetically determined defect that could address the sever deficiency in the synthesis of 25(OH)D in osteomalacia in gene­ral and uremia in particular? The second, is there any confounding factors that could wor­sen the disease in nonuremic osteomalacia,like hypophosphatemia?, third, for our patients, is there any genetically or aquired defect that could address the proximal myopathy as the presenting feature in nonuremic osteomalacia? Considering the clinical presentation of proxi­mal myopathy in both sisters, suggests a gene­tically determined deficiency in synthesis of 25(OH)D in osteomalacia. Similarly the suspi­cion of Fanconi syndrome can not be enter­tained by the absence of glucosuria and amino­aciduria. Hypophosphatemia might be the cul­prit to cause the proximal myopathy, since it's a widely recognized feature in phosphate defi­cient osteomalacia. [7] The unremarkable history of gastrointestinal and hepatobiliary diseases and the negative Anti-gliadin antibody speak against it being as a cause. Osteomalacia is a very common disease all over the world and it may be on the rise in the gulf region also.

 
   References Top

1.Goswani R, Shah P, Ammini AC. Thyrotoxicosis with osteomalacia and proximal myopathy. J Postgrad Med 1993;39:289-90.  Back to cited text no. 1      
2.Saab G, Young DO, Gincherman Y, Giles K, Norwood K, Coyne DW. Prevalence of vita­min D Deficiency and the safety and Effective­ness of Monthly Ergocalciferol in Hemodia­lysis Patients. Nephron Clin Pract 2007;105: 132-8.  Back to cited text no. 2      
3.Allen SC. Biochemical recovery time scales in elderly patients with Osteomalacia. J Royal Soc Med 2004;97:527-30.  Back to cited text no. 3      
4.El-Kishawi Abdulla MW, El-Nahas AM. Renal osteodystrophy: Review of the Disease and its treatment. Saudi J Kidney Dis Transpl 2006; 17(3):373-82.  Back to cited text no. 4      
5.Hruska KA, Saab G, Mathew S, Lund R. Renal osteodystrophy, phosphate hemostasis, and vascular calcification. Semin Dial 2007;20(4): 309-15  Back to cited text no. 5      
6.Anupama YJ, Ravishankar B, Babu KS, Ballal HS. An usual case of hypercalcaemic osteo­malacia: Role of a novel calcimimetic agent. Indian J Nephrol 2007;17(1):17-9.  Back to cited text no. 6      
7.Jacobson JJ, Kalume-Brigido M. Case 97: X­linked hypophosphatemic osteomalacia with Insufficiency fracture. Radiology 2006;240: 607-10.  Back to cited text no. 7      

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Correspondence Address:
Wael Latif Jabur
New Medical Center Specialty Hospital, P.O. Box 7832, Dubai
United Arab Emirates
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PMID: 20061707

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This article has been cited by
1 Association between neurological and rheumatological manifestations in vitamin D deficiency and vitamin D levels
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Pakistan Journal of Medical Sciences. 2013; 29(3)
[Pubmed]



 

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    Abstract
    Introduction
    Case History
    Discussion
    References
 

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