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It has previously been reported that in adult patients with sickle-cell anemia the serum phosphate value and the maximum tubular reabsorption of phosphate per liter of glomerular filtrate (TmP/GFR) were significantly higher than in normal controls. This does not appear to have been studied in children with sickle cell anemia (young sicklers) and this prompted us to assess renal phosphate reabsorption in this group of patients. We looked at serum phosphate level and calculated renal phosphate reabsorption (TP/GFR) in children taking random urine and blood samples at the same time and using the formula TP/GFR = Sp - Up x SCr: UCr, in 30 young sicklers all of whom had normal renal function (mean age 7.3 years) and 40 normal matching controls (mean age 6.5 years). The mean serum phosphate value in young sicklers was significantly lower than in controls (4.3 against 5.3 mg/dl) while the mean value of TP/GFR was 4.09 +/- 0.74 mg/dl in young sicklers compared to 4.65 +/- 0.75 mg/dl in the control group (p = 0.0026). Therefore, the TP/GFR in young sicklers was also significantly lower (p = 0.0026) than in the control group. This may be explained by the high serum level of parathyroid hormone reported previously in patients with sickle cell anemia which is expected to lower phosphate reabsorption (TmP/GFR and TP/GFR are identical in children). The lower serum phosphate value and TP/GFR in younger sicklers seems to be in contrast with the relatively high serum phosphate value and TP/GFR previously reported in adults with sickle cell anemia., (Copyright 1999 S. Karger AG, Basel)

Analysis of available radiographs of the skeletal system in 50 patients suffering from sickle cell anaemia in the Assir Region (South Western height and valley) of the Kingdom of Saudi Arabia taken over a three year period showed a wide spectrum of bone changes. Both infarctions and medullary hyperplasia were common, producing the usual previously reported changes. Spinal changes, mostly osteoporosis and vertebral end plate depression were more prominent in the younger age group. Avascular necrosis of femoral head was common and occurred earlier than in previous reports in the literature. Humeral head and radial head necrosis were also recorded. The overall findings agree with recent reports from both the Eastern and Western regions of the Kingdom that bone changes in SCA are common and could be more severe than in other countries. Complications such as osteomyelitis and fractures were not common.

The concentrations of serum calcium, parathyroid hormone (PTH), 25 Hydroxyvitamin D (25OHD), and 1,25 Dihydroxyvitamin D (1,25(OH)2D) were determined in 99 Saudi patients with sickle cell disease and in 104 matching healthy controls. Serum calcium and 25OHD were significantly lower in the patients, with 14% and 12% of them had serum calcium and 25OHD concentrations, respectively, below the normal range. PTH was significantly higher in the patients, with 31% having values above the normal range. There was no significant difference between patients and controls in regard to 1,25(OH)2D. There was a significant inverse correlation of 25OHD with PTH and a direct correlation of PTH with 1,25(OH)2D. Dietary intake of calcium and vitamin D was adequate in both patients and controls. The results indicate that sickle cell patients have hypocalcaemic tendency associated with supranormal PTH, and imply impaired intestinal absorption of calcium and vitamin D leading to a disturbed calcium metabolism which might contribute to the skeletal changes seen in sickle cell disease.

Serum alkaline phosphatase, alkaline phosphatase isoenzymes, and urinary hydroxyproline excretion were studied in 20 young adult sickle cell patients and 58 matching normal controls. Total alkaline phosphatase was significantly higher in the sickle cell patients than in controls. Heat inactivation test and isoenzyme electrophoresis indicated that bone is the predominant isoenzyme in patients. Hydroxyproline excretion was significantly higher in the sickle cell patients than in controls. Serum total alkaline phosphatase correlated well with urinary hydroxyproline excretion in sickle cell patients (r = 0.73). Both alkaline phosphatase and hydroxyproline increased with age in the sickle cell patients. This study suggests that delayed growth and/or bone destruction may contribute to the elevated levels of alkaline phosphatase and urinary hydroxyproline.

In a 3-year period, eight cases of cerebrovascular accident were seen out of 400 patients with sickle cell disease residing at high and low altitudes of Asir Province of Saudi Arabia. They were all Saudi nationals and comprised five boys and three girls of ages ranging from 3.5 to 9 years. They had varied clinical presentations of their cerebrovascular accident. Cranial computed tomography in seven of them showed abnormality in the region of the middle cerebral circulation. Management and some suggested factors contributing to the occurrence of the cerebrovascular accident are discussed.