Intravenous paricalcitol for treatment of secondary hyperparathyroidism in children on hemodialysis

BACKGROUND

Secondary hyperparathyroidism is a common complication in children receiving hemodialysis. Active vitamin D is an effective therapy, but its use is often limited by hypercalcemia and increased calcium x phosphorus (Ca x P) product. Paricalcitol, a selective vitamin D receptor activator, causes less sustained hypercalcemia and increase in Ca x P product than calcitriol and has been used effectively in adult hemodialysis patients.

STUDY DESIGN

Double blind, placebo-controlled.

SETTING & PARTICIPANTS

Hemodialysis units and pediatric subjects receiving hemodialysis.

INTERVENTION

After a washout period of 2 to 6 weeks, 29 subjects aged 5 to 19 years received either paricalcitol or placebo for up to 12 weeks (0.04 mug/kg if initial intact parathyroid hormone [iPTH] level < 500 pg/mL [ng/L]; 0.08 mug/kg if initial iPTH level > 500 pg/mL [ng/L]). The dose was increased by 0.04 mug/kg every 2 weeks until there was a 30% decrease in iPTH level from baseline or calcium level greater than 11 mg/dL (>2.74 mmol/L) or Ca x P product greater than 75 mg(2)/dL(2) (>6.04 mmol(2)/L(2)).

OUTCOMES & MEASUREMENTS

Two consecutive 30% decreases from baseline in iPTH levels and safety of paricalcitol, including hypercalcemia and increase in Ca x P product.

RESULTS

60% of the paricalcitol group had 2 consecutive 30% decreases from baseline iPTH levels compared with 21% in the placebo group (P = 0.06). The paricalcitol group had a mean decrease in iPTH level of 164 pg/mL (ng/L), whereas the placebo group had a mean increase of 238 pg/mL (ng/L; P = 0.03). There was no difference from baseline to final visit in calcium, phosphorus, or Ca x P product values in either group.

LIMITATIONS

Low power to detect differences in safety between groups and a short-term study.

CONCLUSION

Paricalcitol decreased iPTH levels in children receiving hemodialysis with no significant changes in serum calcium, phosphorus, or Ca x P product values during the course of the study.

A new era in phosphate binder therapy: what are the options?

Dietary restriction of phosphorus and current dialysis prescription are unable to maintain phosphorus levels within the recommended range (2.7-5.5 mg/dl) in patients with advanced chronic kidney disease (CKD). Therefore, phosphate binders that limit the absorption of dietary phosphorus are commonly prescribed for this patient group. The first phosphate binders were introduced more than 30 years ago and included aluminum salts; however, although effective binders, the use of these agents was subsequently restricted because of concerns over aluminum accumulation in the central nervous system, bone, and hematopoietic cells. In subsequent years, calcium salts, namely calcium carbonate and calcium acetate, became the most widely used phosphate binders; however, increasing evidence now suggests that prolonged use of these agents increases the total body calcium load, induces adynamic bone, and potentially increases the risk of cardiovascular and soft tissue calcification. Sevelamer is the first phosphate-binding agent that is non-absorbed, calcium-free, and metal-free. To date, this agent has been shown to effectively control serum phosphorus levels in patients with CKD. It may also attenuate coronary and aortic calcification and has a number of other beneficial effects on lipid metabolism and inflammation among others. Lanthanum carbonate is another new agent that is reported to provide similar phosphate control to calcium-based phosphate binders but concerns that the long-term administration of such compound may lead to tissue accumulation may limit its use.

Osteomalacia in a hemodialysis patient receiving an active vitamin D sterol

BACKGROUND

A 17-year-old Filipino male hemodialysis patient presented for renal transplant evaluation. He had significant skeletal abnormalities characterized by bone pain, an inability to walk, and secondary hyperparathyroidism despite therapy with an active vitamin D sterol (paricalcitol).

INVESTIGATIONS

The patient underwent a physical examination, and his serum levels of calcium, phosphorus, alkaline phosphatase, parathyroid hormone, aluminum and 25-hydroxycholecalciferol (25OH-vitamin D) were determined. X-rays of hips and lower extremities, MRI, and bone histomorphometry after double tetracycline labeling were performed.

DIAGNOSIS

Osteomalacia associated with low 25OH-vitamin D levels.

MANAGEMENT

Monthly therapy with ergocalciferol (vitamin D2) and discontinuation of paricalcitol.

Survival predictability of time-varying indicators of bone disease in maintenance hemodialysis patients

Although renal osteodystrophy and vitamin D analogs may be related to survival in maintenance hemodialysis (MHD) patients, most studies have examined associations between baseline values and survival without accounting for variations in clinical and laboratory measures over time. We examined associations between survival and quarterly laboratory values and administered paricalcitol in a 2-year (July 2001-June 2003) cohort of 58,058 MHD patients from all DaVita dialysis clinics in USA using both time-dependent Cox models with repeated measures and fixed-covariate Cox models with only baseline values. Whereas hypercalcemia and hyperphosphatemia were robust predictors of higher death risk in all models, the association between serum calcium and mortality was different in time-varying models. Changes in baseline calcium and phosphorus values beyond the Kidney Disease Outcome Quality Initiative recommended targets were associated with increased mortality. Associations between high serum parathyroid hormone and increased death risk were masked by case-mix characteristics of MHD patients. Time-varying serum alkaline phosphatase had an incremental association with mortality. Administration of any dose of paricalcitol was associated with improved survival in time-varying models. Controlling for nutritional markers may introduce overadjustment bias owing to their strong collinearity with osteodystrophy surrogates. Whereas both time-dependent and fixed-covariate Cox models result in similar associations between osteodystrophy indicators and survival, subtle but potentially clinically relevant differences between the two models exist, probably because fixed models do not account for variations of osteodystrophy indices and changes in medication dose over time.

Role of parathyroid hormone and therapy with active vitamin D sterols in renal osteodystrophy

Renal osteodystrophy (ROD) represents a spectrum of bone lesions ranging from a high-turnover to a low-turnover state. The expression of the histologic bone lesions is modulated by parathyroid hormone (PTH), vitamin D, calcium, phosphorus, and aluminum that act as major regulators of osteoblastic activity and bone formation rate. The availability of immunometric PTH assays has allowed reasonable prediction of the subtypes of bone lesions in patients with chronic kidney disease (CKD). PTH levels as measured by these assays, however, may not reflect the true bone turnover state during treatment with intermittent active vitamin D. Early diagnosis and appropriate treatment of renal bone disease are essential in preventing the debilitating consequences of ROD on the growing skeleton. Calcitriol and calcium-containing phosphate binders have been the mainstay of treatment for secondary hyperparathyroidism. Complications such as hypercalcemia, vascular calcifications, and the development of adynamic bone may arise from aggressive treatment. New vitamin D analogs and calcium-free phosphate binders are promising in terms of limiting these complications. The management of ROD should be tailored to maintain normal rates of bone formation and turnover with age-appropriate serum calcium and phosphorus levels and with serum PTH levels that correspond to normal rates of skeletal remodeling. These treatment goals would maintain bone health, maximize growth potential, and prevent the development of soft tissue and vascular calcifications.

Sevelamer controls parathyroid hormone-induced bone disease as efficiently as calcium carbonate without increasing serum calcium levels during therapy with active vitamin D sterols

Little is known about the impact of various phosphate binders on the skeletal lesions of secondary hyperparathyroidism (2 degrees HPT). The effects of calcium carbonate (CaCO3) and sevelamer were compared in pediatric peritoneal dialysis patients with bone biopsy-proven 2 degrees HPT. Twenty-nine patients were randomly assigned to CaCO3 (n = 14) or sevelamer (n = 15), concomitant with either intermittent doses of oral calcitriol or doxercalciferol for 8 mo, when bone biopsies were repeated. Serum phosphorus, calcium, parathyroid hormone (PTH), and alkaline phosphatase were measured monthly. The skeletal lesions of 2 degrees HPT improved with both binders, and bone formation rates reached the normal range in approximately 75% of the patients. Overall, serum phosphorus levels were 5.5 +/- 0.1 and 5.6 +/- 0.3 mg/dl (NS) with CaCO3 and sevelamer, respectively. Serum calcium levels and the Ca x P ion product increased with CaCO3; in contrast, values remained unchanged with sevelamer (9.6 +/- 01 versus 8.9 +/- 0.2 mg/dl; P < 0.001, respectively). Hypercalcemic episodes (>10.2 mg/dl) occurred more frequently with CaCO3 (P < 0.01). Baseline PTH levels were 980 +/- 112 and 975 +/- 174 pg/ml (NS); these values decreased to 369 +/- 92 (P < 0.01) and 562 +/- 164 pg/ml (P < 0.01) in the CaCO3 and the sevelamer groups, respectively (NS between groups). Serum alkaline phosphatase levels also diminished in both groups (P < 0.01). Thus, treatment with either CaCO3 or sevelamer resulted in equivalent control of the biochemical and skeletal lesions of 2 degrees HPT. Sevelamer, however, maintained serum calcium concentrations closer to the lower end of the normal physiologic range, thereby increasing the safety of treatment with active vitamin D sterols.

Calcification of the coronary arteries in the absence of atherosclerotic plaque

Arterial calcification in the coronary arteries frequently indicates concomitant atherosclerotic plaque but can be present in the medial layers with no evidence of plaque. Calcification of the medial layer of arteries is seen most often in the peripheral arteries but also is widely recognized In the coronary arteries. We describe 2 patients who had marked medial and intimal calcification of the coronary arteries with little or no accompanying atherosclerosis.

Intravenous calcitriol for treatment of hyperparathyroidism in children on hemodialysis

This double-blind, placebo-controlled study evaluated the safety and efficacy of intravenous (i.v.) calcitriol (Calcijex) for treatment of secondary hyperparathyroidism (secondary HPT) in pediatric end-stage renal disease (ESRD) patients on hemodialysis (HD). After a 2 to 6-week washout period of all vitamin D compounds, patients with two consecutive PTH values > 400 pg mL(-1), calcium levels < or = 10.5 mg dL(-1) and calcium x phosphorus product values < or = 70 mg2 dL(-2) were eligible for the treatment phase. Patients received a bolus injection of calcitriol or placebo three times a week, immediately after dialysis for up to 12 weeks. Initial doses (0.5-1.5 microg) were based on the severity of secondary HPT. The dose was increased every two weeks by 0.25 microg until there was at least a 30% decrease in PTH from baseline, or Ca > 11.0 mg dL(-1), or Ca x P > 75 mg2 dL(-2). Overall, 11/21 (52%) patients in the calcitriol group had two consecutive > or = 30% decreases from baseline in serum PTH compared with 5/26 (19%) patients in the placebo group (P=0.03). The mean total alkaline phosphatase decreased from 274 to 232 IU L(-1) in the calcitriol group and increased from 547 to 669 IU L(-1) in the placebo group (P=0.002). The mean bone-specific alkaline phosphatase decreased from 72.5 to 68 microg L(-1) in the calcitriol group and increased from 105.3 to 148.5 microg L(-1) in the placebo group (P=0.03). The incidence of two consecutive occurrences of elevated calcium x phosphorus (Ca x P > 75 mg2 dL(-2)) product was higher in the calcitriol group than in the placebo group (P=0.01). Two consecutive occurrences of phosphorus > 6.5 mg dL(-1) occurred in 71% of the calcitriol group and 46% of the placebo group (P=0.14). Calcium levels > 10.5 mg dL(-1) were more common in the calcitriol group than in the placebo group (P=0.01). There was a direct relationship between serum phosphorus concentration and the percentage change in PTH from baseline in both the calcitriol group (r=0.46; P<0.0001) and the placebo group (r=0.21; P=0.0005). This study demonstrates that i.v. calcitriol, at initial doses of 0.5-1.5 microg, effectively reduces PTH levels in pediatric HD patients and that patients should be closely monitored for hyperphosphatemia and elevated Ca x P product.

Are new vitamin D analogues in renal bone disease superior to calcitriol?

Progression of chronic kidney disease is associated with an early reduction in serum calcitriol levels; thus, therapy with calcitriol should be initiated early in the course of chronic kidney disease to prevent the development of secondary hyperparathyroidism. Initial studies demonstrated a potential role of calcitriol in the prevention of growth retardation in children with chronic kidney disease prior to dialysis. But the optimal parathyroid hormone (PTH) levels that will maximize growth response during calcitriol treatment remain to be defined. Therapy with calcitriol has been shown to control the biochemical and skeletal manifestations of secondary hyperparathyroidism, but patients developed hypercalcemia, hyperphosphatemia and adynamic osteodystrophy. Thus, new vitamin D analogues with a lower hypercalcemic response have been developed. Although comparative studies are lacking, current evidence indicates that these new active vitamin D sterols (19-nor-paracalcitol and doxercalciferol) adequately control secondary hyperparathyroidism with minimal changes in serum calcium and phosphorus levels during treatment with calcium-containing binders. The long-term effect of such therapies on the skeleton and the process of vascular calcifications remain to be evaluated.

New PTH assays and renal osteodystrophy

Parathyroid hormone (PTH) levels have been used instead of bone histomorphometric analysis in renal failure, but the assessment of tetracycline-labeled bone biopsy remains the most reliable method to diagnose the different subtypes of renal osteodystrophy. The availability of the first-generation immunometric PTH assay (1(st) PTH-IMA) allowed the distinction between the different types of renal bone diseases. However, 1(st) PTH-IMA not only detects the intact hormone PTH(1-84), but also additional PTH truncated fragments. A second-generation immunometric PTH assay (2(nd) PTH-IMA) recognizes only PTH(1-84) and possible PTH fragments that are truncated at the carboxyl-terminus, but not PTH(7-84). In addition, whether assessment of the ratio PTH(1-84) and amino-terminally truncated PTH(1-84) fragments is a better predictor of bone turnover remains controversial. An initial study using the 2(nd) PTH-IMA suggested that the ratio between PTH(1-84) and amino-terminally truncated PTH(1-84) fragments more accurately predicts bone turnover in adult patients treated with hemodialysis. However, subsequent studies using the Scantibodies assay have failed to better predict the underlying bone disease in adults undergoing maintenance hemodialysis. Furthermore, a different 2(nd) PTH-IMA (Immutopics) with similar, but not identical, in vitro characteristics did not show a superior predictive value of the ratio in pediatric patients treated with peritoneal dialysis. Although the 2(nd) PTH-IMA may provide important new insights into the physiology of parathyroid gland function, at present, measurement of PTH using either 1(st) or 2(nd) PTH-IMAs provides similar accuracy for predicting bone turnover in patients treated with dialysis. Thus, the current data do not yet support the claim that 2(nd) PTH-IMAs provide an advantage over 1(st) PTH-IMAs for the diagnosis of the different subtypes of renal bone diseases.

Bone histology in steroid-treated children with non-azotemic nephrotic syndrome

Patients with nephrotic syndrome (NS) and normal glomerular filtration rate (GFR) frequently exhibit abnormalities of calcium and vitamin D homeostasis, mainly hypocalcemia and reduced circulating vitamin D metabolites. These abnormalities have been linked to alterations of bone histology in adults with non-azotemic NS, particularly osteomalacia and excessive bone resorption. Whether similar abnormalities of bone histology occur in children and adolescents with NS, particularly in those requiring prolonged treatment with corticosteroids, remains largely unknown. Thus, bone histomorphometry and selected bone-modulating hormones were studied in eight children (aged 2-16 years) with normal GFR (range 85-169 ml/min per 1.73 m(2)) and NS. All patients received corticosteroids for at least 12 months prior to bone biopsy. At the time of bone biopsy, the urine protein/creatinine ratio was elevated (2.1+/-3.6), while the average concentrations of parathyroid hormone (36+/-13 pg/ml), 25-hydroxyvitamin D [25(OH) D] (22+/-14 ng/ml), and 1,25(OH)(2)D (59+/-22 pg/ml) were normal. Bone histomorphometry displayed focal osteomalacia (OM) and mild increased bone resorption in most patients. The mineralization lag time, an indicator of the degree of osteomalacia, correlated with the time elapsed since the original diagnosis of NS ( r=0.93, P<0.0005). Overt hyperparathyroidism was not evident, but increased eroded perimeter and elevated bone formation rate (BFR) were evident in two patients, suggesting high-turnover bone disease. The BFR was inversely correlated with the administered dose of prednisone at the time of biopsy ( r=-0.78, P<0.05) and one patient exhibited low bone turnover changes. The growth velocity standard deviation score (SDS) at time of biopsy ranged from -1.6 to 3.2, resulting in a height SDS range of -1.9 to 0.6. The height SDS at time of bone biopsy correlated inversely with the dose of administered glucocorticoid ( r=-0.71, P<0.05) and with the duration of the disease ( r=-0.7, P=0.05). These data, albeit preliminary, demonstrate that children with NS treated with prolonged corticosteroid therapy exhibit bone histopathological changes without a concomitant impairment in GFR. While the OM appears to be related to the disease process, the alterations of bone formation and the adynamic changes are likely the result of the corticosteroid therapy. The potential consequences of these findings on adult bone mass and ultimate height deserve further studies.

Special aspects of renal osteodystrophy in children

Renal osteodystrophy represents a spectrum of skeletal lesions that range from high-turnover to low-turnover bone disease. Similar factors are involved in the pathogenesis of renal osteodystrophy in adult and pediatric patients with chronic kidney disease (CKD). However, growth retardation and the development of bone deformities are specific complications that occurred in pediatric patients with CKD. Metabolic acidosis, renal osteodystrophy, malnutrition, and disturbances in the insulin growth factor (IGF)/growth hormone (GH) are among the main factors involved and they are discussed briefly in this article. In addition to disturbances in bone remodeling, longitudinal bone growth occurs at the growth plate cartilage by endochondral ossification. Although young rats with experimental CKD have growth retardation, the characteristics of the growth plate are markedly different between animals with severe secondary hyperparathyroidism and those with calcium-induced adynamic osteodystrophy. These disturbances may suggest potential molecular mechanisms by which endochondral bone formation may be altered in renal failure, consequently leading to growth retardation.

Sevelamer hydrochloride: an effective phosphate binder in dialyzed children

This pilot study was designed to evaluate the efficacy and acceptability of sevelamer hydrochloride as a phosphate binder in pediatric patients treated with dialysis. A 6-month open-label trial of sevelamer hydrochloride (Renagel) was initiated in 17 patients, aged 11.8+/-3.7 years, undergoing hemodialysis ( n=3) or peritoneal dialysis ( n=14). Following a 2-week washout period of the phosphate binders, serum phosphorus increased from 5.2+/-1.3 mg/dl to 7.5+/-2.2 mg/dl ( P<0.0002). After initiation of therapy with sevelamer hydrochloride, serum phosphorus levels decreased to 6.2+/-1.2 mg/dl ( P<0.01) during the first 8 weeks and final values were 6.3+/-1.5 mg/dl. Serum calcium concentration decreased during the washout period from 9.4+/-0.9 mg/dl to 8.9+/-1.5 mg/dl ( P<0.01); values remained unchanged thereafter. The serum calcium-phosphorus ion product decreased during the first 8 weeks and values did not change subsequently. Serum bicarbonate, parathyroid hormone, total cholesterol, low-density lipoprotein and high-density lipoprotein cholesterol, and triglyceride levels did not change. The initial prescribed dose of sevelamer hydrochloride was 121+/-50 mg/kg (4.5+/-5 g/day) and the final prescribed dose was 163+/-46 mg/kg (6.7+/-2.4 g/day). Sevelamer hydrochloride was well tolerated and without adverse effects related to the drug.

Sudden blindness caused by anterior ischemic optic neuropathy in 5 children on continuous peritoneal dialysis1 1Published partially (case 3) in abstract form in Arch Ped 7:437, 2000, and in Pediatr Nephrol 16:C4, 2001

The authors report the occurrence of sudden blindness in 5 children (mean age, 32 months; range, 11 to 60) during continuous peritoneal dialysis regimen. All children presented with loss of light perception, visual fixation and ocular pursuit, and bilateral mydriasis unreactive to bright light. Fundoscopic examination found signs of anterior ischemic optic neuropathy with disc swelling, edema, and hemorrhages. Whereas 1 patient was dehydrated, the 4 other patients appeared well and not dehydrated. Nevertheless, blood pressure was below the normal range in all of them. Therefore, hypovolemia is highly suspected to have been the cause of ischemic optic neuropathy in all cases. Treatment consisted of steroids (4 patients), anticoagulation or antiagregation drugs (3 patients), plasma or macromolecules infusions (2 patients), vasodilatators (2 patients), and transient dialysis interruption (1 patient). One child with hepatic cirrhosis died 4 days later of acute liver insufficiency owing to ischemic hepatic necrosis. The other children had only partial improvement of vision during the following months. Because the prognosis of ischemic optic neuropathy is very poor, diagnosis and treatment of chronic hypovolemia in children on continuous peritoneal dialysis is essential to prevent such a devastating complication.

Bone density measurements in pediatric patients with renal osteodystrophy

Peripheral quantitative computed tomography (pQCT) can selectively measure the densities of cortical and trabecular bone, but there is limited information about its use in patients with renal osteodystrophy. Thus pQCT (Norland XCT-2000, Stratec, Pforzheim, Germany) was performed at the ultradistal radius in 21 patients aged 16+/-3.6 (SD) years on continuous cycling peritoneal dialysis. Trabecular bone density (TBD) was higher in patients, 206+/-16 mg/cm(3), than in controls, 182.7+/-24.8 mg/cm(3) ( P<0.0001), whereas cortical bone density (CBD) was lower in patients, 946.5+/-147.5 mg/cm(3), than in controls, 1,153+/-25.4 mg/cm(3) ( P<0.001). TBD was inversely correlated with age ( r=-0.59, P=0.05), height ( r=-0.59, P<0.01), and weight ( r=-0.51, P<0.05). In contrast, CBD was positively correlated with age ( r=0.53, P<0.05), height ( r=0.56, P<0.05), and weight ( r=0.53, P<0.05). CBD was inversely related to serum alkaline phosphatase ( r=-0.71, P<0.001) and parathyroid hormone levels ( r=-0.50, P<0.05). In patients with adynamic bone, TBD was less, 192+/-9 mg/cm(3), than in those with high-turnover lesions, 215+/-13 mg/cm(3), P<0.001. CBD, however, was lower in patients with high-turnover lesions, 900+/-151 mg/cm(3), than in those with low turnover, 1,022+/-111 mg/cm(3), P<0.05. Compared with controls, in patients with high-turnover lesions, CBD was lower ( P<0.0001) and TBD higher ( P<0.0001). These findings suggest that pQCT may be an additional tool in the assessment of renal osteodystrophy.

Similar predictive value of bone turnover using first- and second-generation immunometric PTH assays in pediatric patients treated with peritoneal dialysis

BACKGROUND

Accurate measurements of the concentration of parathyroid hormone (PTH) in serum or plasma are essential for the proper assessment of renal osteodystrophy. The first-generation immunometric PTH assay (1st PTH-IMA) not only detects the intact hormone, but also additional PTH fragments truncated at the amino N-terminally truncated PTH-derived fragments [ntPTH(1-84)]. A second-generation immunometric PTH assay (2nd PTH-IMA) recognizes only PTH(1-84) and possibly PTH fragments that are truncated at the carboxyl-terminus but not PTH(7-84). Whether estimates of the ratio between PTH(1-84) and ntPTH(1-84) fragments are a better predictor of bone turnover remains controversial.

METHODS

Thirty-three patients aged 12.8 +/- 4.4 years treated with continuous cycling peritoneal dialysis (CCPD) for 13 +/- 9 months underwent iliac crest bone biopsy. PTH levels were measured by two newly developed first-generation and second-generation PTH-IMA. The ntPTH(1-84) fragments were calculated by subtracting PTH values determined using the 2nd PTH-IMA from values obtained using 1st PTH-IMA that detects both PTH(1-84) and relatively large ntPTH(1-84).

RESULTS

Determinations of PTH levels by both assays were highly correlated (r = 0.89, P < 0.001). The relationships between first-generation and second-generation PTH-IMA and bone formation were similar (r = 0.67, P < 0.0001 and r = 0.64, P < 0.0001, respectively). When patients were grouped according to the presence or absence of secondary hyperparathyroidism, the ratio PTH(1-84) to ntPTH(1-84) did not differ between groups.

CONCLUSION

PTH concentrations determined by either the first- or the second-generation PTH-IMA were found to be better predictors of bone formation than the PTH(1-84) to ntPTH(1-84) fragments ratio.

Outcome of slipped capital femoral epiphysis in renal osteodystrophy

The cases of renal osteodystrophy-associated slipped capital femoral epiphysis in 11 consecutive patients were reviewed. Nine patients had bilateral involvement, totaling 20 hips. The mean age at presentation was 10.6 years. Slip location was physeal in 13 and metaphyseal in seven hips. All patients had prompt medical treatment of their bone disease, and nine patients underwent surgical stabilization. Fixation consisted of multiple custom-machined Steinmann pins that were smoothed distally but threaded proximally, allowing continued proximal femoral growth. The mean radiographic and clinical follow-up was 5.7 years and 9.1 years, respectively. Slips stabilized in 14 of 16 operated hips (88%), whereas one patient with inadequate renal disease control had slip progression requiring subsequent subtotal parathyroidectomy and repeat fixation. Combined medical management and surgery with custom-machined pins prevented slip progression while allowing continued physeal growth.