|Year : 2015 | Volume
| Issue : 1 | Page : 44-47
Renal osteodystrophy presenting predominantly with osteosclerosis
Oriazo Theophilus Akhigbe, Pamella Faith Isioma Irabor
Department of Radiology, Irrua Specialist Teaching Hospital, Irrua, Edo State, Nigeria
|Date of Web Publication||26-Feb-2015|
Oriazo Theophilus Akhigbe
P. O. Box 508, Benin City, Edo State
Renal osteodystrophy is a skeletal pathology characterized by bone mineralization deficiency, which is a direct result of endocrine and electrolyte derangements that accompany chronic kidney disease. We hereby present a case of a 60-year-old man with chronic renal failure showing classical osseous changes of osteomalacia and osteosclerosis.
Keywords: Osteodystrophy, osteosclerosis, renal
|How to cite this article:|
Akhigbe OT, Irabor PI. Renal osteodystrophy presenting predominantly with osteosclerosis. Sahel Med J 2015;18:44-7
| Introduction|| |
Renal (uremic) osteodystrophy is a combination of disorder of mineral and bone metabolism associated with chronic renal insufficiency leading to high-urea levels in the blood. ,, It represents a spectrum of skeletal lesions that range from high turnover to low-turnover bone disease. However, the most frequent cause of renal osteodystrophy is secondary hyperparathyroidism, which results in high-bone turnover. ,,, These bone changes can occur early and are dependent on the calcium-phosphorus homeostasis. We present a patient with chronic renal failure showing classical osseous changes of osteomalacia and osteosclerosis.
| Case report|| |
Mr. I.D. is a 60-year-old retired driver who presented to the accident and emergency department of University of Benin Teaching Hospital with 1-month history of anorexia, vomiting, facial and leg swelling, nausea, inability to walk and low-urine output. He is a known hypertensive of 20 years duration. In March 2003, he had a cerebrovascular accident. He is not a known diabetic or sickle cell disease patient. He has never undergone dialysis. He is married to one wife and has six children. He does not smoke cigarette but takes alcoholic drinks occasionally.
On examination, he was pale, afebrile and ill-looking but well-oriented. There was also no neck swelling. His pulse was of small volume, blood pressure 150/110 mmHg, heart rate 80 beats/min. Heart sound I and II were normal with no murmurs. His chest was clear clinically. Abdomen was normal with no ascites.
The reports of investigations done were as follows: Hematocrit (13%), white blood cell (3,500/ml) erythrocyte sedimentation rate (140 mm fall in 1 h), fasting blood sugar (46 mg/dL), urea (232 mEq/L), sodium (110 mEq/L), potassium (3.2 mEq/L), Bicarbonate (14 mEq/L), chloride (77 mEq/L), serum creatinine (4.5 mg/dL). Urine analysis showed proteinuria 3 + , and many pus cells. Phosphate level was elevated, while calcium level was low.
Abdominal ultrasound showed bilaterally shrunken and hyperechoic kidneys with loss of corticomedullary differentiation. His prostate gland was not enlarged. His chest radiograph showed normal cardiac shadow with aortic unfolding. The lung fields were normal. However, the visualized bones were chalky white with splaying and severe cupping of the anterior ends of the ribs giving the rachitic rosary sign [Figure 1]. Plain radiographs of the lumbosacral spine showed sclerosis of the upper and lower thirds of the vertebral bodies giving the "rugger - jersey" spine. There were also vertebral marginal osteophytes. His pelvic radiograph showed chalky white sclerosis of the pelvis and upper femora with multiple pathological fractures of the left femur [Figure 2]. There was also a linear lucency across the inferior ramus of the right pubis suggestive of looser's zone. Both iliac wings showed alternating bands of sclerosis and lucencies with osteophytoses of both acetabular roofs. His hand radiograph showed patchy sclerosis of the visualized bones with normal phalangeal tufts and no evidence of cortical erosions [Figure 3].
|Figure 1: Chest radiograph showing cupping of anterior end of the ribs (white arrows). There is generalized sclerosis of all the visualized bones|
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|Figure 2: Pelvic radiograph showing chalky white bones with pathologic fractures of left femoral neck and shaft (white arrow). There is a looseræs zone in the right inferior ramus (white thick arrow)|
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A diagnosis of uremic osteodystrophy with predominance of osteosclerosis and osteomalacia was made. Dialysis was immediately recommended, and the patient's serum urea and creatinine level came down to 98 mEq/L and 2.4 mg/dL, respectively after three sessions.
| Discussion|| |
Disorders in the metabolism of Vitamin D which is of renal origin is primarily implicated in uremic osteodystrophy. Hydroxylation of 25, hydroxycholecalciferol to 1, 25 dihydroxycholecalciferol (DHCC) (1, 25 DHCC) takes place in the kidney. This 1, 25 DHCC is the active hormonal form of Vitamin D and it acts on several target organs:  the intestine, where it initiates synthesis of a calcium-binding protein in the mucosa, thus promoting active absorption of calcium and phosphorus from the intestinal contents and the kidney which stimulates the production of relatively inert metabolite 24, 25 Dihydroxy cholecalciferol (24, 25 DHCC) thus limiting the production of 1, 25 DHCC by a negative feedback mechanism.
In the presence of chronic renal failure and uremia, there is a reduction in the availability of 1, 25 DHCC which in turn leads to low-calcium absorption from the intestines and renal tubules, therefore, leading to hypocalcemia and phosphate retention (hyperphosphatemia). The parathyroid gland then releases more parathormone in order to increase serum calcium levels. Parathormone causes increase in intestinal calcium absorption; increased bone turnover especially resorption and increased tubular reabsorption of calcium. This is the pathophysiology of secondary hyperparathyroidism. ,,,,,,,,,
There are four different combinations of musculoskeletal abnormalities described:  Osteomalacia in adults/rickets in children, secondary hyperparathyroidism with osteitis fibrosa cystica + soft tissue calcification, osteosclerosis and soft tissue and vascular calcifications.
The patient presented here showed skeletal features of osteosclerosis and osteomalacia. There was no evidence of soft tissue or vascular calcification. Radiological investigation of patients with uremic osteodystrophy secondary to chronic renal failure requires the use of ultrasonography, radiography, scintigraphy, computed tomography and magnetic resonance imaging. , Bone histomorphometry remains the gold standard for the diagnosis of renal osteodystrophy histologically.  However, the low-acceptance grade by patients makes bone biopsy a rarely performed and not easily repeatable investigation.  Only plain radiography was employed in the patient under discussion.
Ultrasonography can be a useful, economical and noninvasive method in the evaluation of renal osteodystrophy, especially in the imaging of soft tissue, which include the parathyroid glands, pathological changes of the joints and in the detection of metastatic calcification. , It also can demonstrate hyperplasia/hypertrophy of the parathyroid glands. Ultrasound scan of the abdomen was done for the patient presented.
Although numerous new imaging modalities have been introduced, plain film radiography, especially fine quality hand radiography, still represents the most widely used examination. , Simple radiography will show changes of secondary hyperparathyroidism such as cortical resorption of phalanges and lamina dura, "rugger - jersey" spine, changes of osteomalacia and rickets, "pepper pot skull" and "rotten fence postsign" in the femoral neck. The patient presented showed no signs of phalangeal resorption but patchy areas of osteosclerosis with the rugger jersey spine. He also showed a looser's zone in the right inferior pubic ramus. In addition, there was a generalized osteosclerosis of the thorax, pelvis and femur with a pathological fracture of the right femoral neck and shaft. Soft tissue calcifications, which may be evident was not seen in the case presented.
Occasionally brown tumors and pathological fractures are seen both in flat and long bones. ,,,,, The patient presented had pathologic fractures of the right femoral neck and shaft. Cranial thickening increased cranial size and massive calvarial hyperostosis are the features seen in uremic leontiasis ossium otherwise known as "big head disease" of uremic osteodystrophy.  The skull radiograph of the patient presented was essentially normal.
Scintigraphy is also of value in hyperparathyroidism and to localize the site of an adenoma where surgical treatment is being considered. More recent position emission tomography scanning has been found to be helpful in more difficult cases. ,,
The advantage computed tomography has over plain radiography is in its ability to pick up and demonstrate soft tissue and vascular calcifications better.  Magnetic resonance imaging provides detailed information about bone marrow and parathyroid glands, but will not show soft tissue and vascular calcifications.  These two modalities of investigation were not done for the patient in this presentation. Disease processes which cause the osteosclerosis with or without the rugger jersey spine include Paget's disease, osteopetrosis, lymphoma, osteoblastic metastases, fluorosis and myelofibrosis. One factor to keep in mind when differentiating renal osteodystrophy from these other conditions is that the rugger jersey spine sign is multisegmental as it affects multiple vertebral bodies.  This differs from the uniform increased density seen in Paget's disease, osteoblastic metastases or lymphoma. Osteoblastic metastasis and lymphoma produce the so-called IVORY vertebra which may affect a solitary vertebral body. ,
Rugger jersey spine can be differentiated from the "picture frame" appearance of the vertebral body seen in Paget's disease. The cortex of all sides of the vertebral body is thickened in Paget's disease due to disorganized new cortical bone formation after excessive osteoclastic activity, which caused the resorption of normal bone, whereas the characteristic sclerosis of renal osteodystrophy is seen only at the superior and inferior endplates. ,, Complete skeletal survey, in addition to pertinent clinical and laboratory data aids in distinguishing these disorders. 
A common cause of osteomalacia in patients with end-stage renal disease is aluminum intoxication. However, serum aluminum was not determined in this case presented.
The management of chronic renal failure involves repeated sessions of dialysis but definitive treatment is by renal transplantation. Prognosis is variable, but transplant rejection is associated with a high-mortality rate.
| Conclusion|| |
Renal osteodystrophy is a common long-term complication of end-stage renal disease. A case of renal osteodystrophy in a 60-year-old man with chronic renal failure showing classical radiographic bone changes of osteomalacia and osteosclerosis is presented. Though the etiology of renal osteodystrophy is not completely understood, two mechanisms that predominate in the etiology, that is secondary hyperparathyroidism and Vitamin D metabolism are discussed. The radiological and biochemical investigations, as well as differential diagnosis, were also discussed. The management which involves repeated sessions of dialysis and ultimately renal transplant is mentioned. The patient presented has since undergone three sessions of hemodialysis with signs of improvement.
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[Figure 1], [Figure 2], [Figure 3]