Health-related quality of life of X-linked hypophosphatemia in Spain.

BACKGROUND: Health-related quality of life (HRQoL) of patients with X-linked hypophosphatemia (XLH) is lower than that of both the general population and the patients with other chronic diseases, mainly due to diagnostic delay, treatment difficulties, poor psychosocial support, and problems with social integration. Early diagnosis and optimal treatment are paramount to control the disease in patients with XLH, avoid complications, and maintain or improve their HRQoL. We, therefore, analyzed the HRQoL of pediatric and adult patients with XLH treated with conventional therapy in Spain. RESULTS: We used several versions of the EuroQol-5 dimensions (EQ-5D) instrument according to the age of patients with XLH. Then we compared the HRQoL of patients to that of the general Spanish population. Children with XLH (n = 21) had moderate problems in walking about (61.9%), washing or dressing themselves (9.52%), and performing their usual activities (33.33%). They also felt moderate pain or discomfort (61.9%) and were moderately anxious or depressed (23.81%). Adults with XLH (n = 29) had lower HRQoL, with problems in walking (93%, with 3.45% unable to walk independently), some level of pain (86%, with 3.45% experiencing extreme pain), problems with their usual activities (80%) and self-care (> 50%), and reported symptoms of anxiety and/or depression (65%). There were important differences with the general Spanish population. CONCLUSIONS: XLH impacts negatively on physical functioning and HRQoL of patients. In Spanish patients with XLH, the HRQoL was reduced despite conventional treatment, clearly indicating the need to improve the therapeutic approach to this disorder.

X-linked hypophosphatemia (XLH) is a severe inherited disease. It is caused by loss of phosphorus by kidneys. As a result, blood level of phosphorus is low, affectingX-linked hypophosphatemia (XLH) is a severe inherited disease. It is caused by loss of phosphorus by kidneys. As a result, blood level of phosphorus is low, affecting bones and muscles. Patients can have growth retardation, short stature, rickets, limb deformities, pain and other health problems despite traditional treatment. Consequently, their quality of life can be very bad. However, a recently available new treatment (burosumab) can improve this quality of life. We studied the quality of life of children and adults with XLH treated with traditional treatment in Spain. Results showed that children had moderate problems, but adults reported moderate-to-severe problems in walking and performing their usual activities and self-care. Pain and anxiety and/or depression were very frequent. There were important differences with the general Spanish population. Moreover, we also found that XLH is associated to high healthcare cost and even higher socioeconomic cost. Our results highlight the need of improving the treatment of XLH.bones and muscles. Patients can have growth retardation, short stature, rickets, limb deformities, pain and other health problems despite traditional treatment. Consequently, their quality of life can be very bad. However, a recently available new treatment (burosumab) can improve this quality of life. We studied the quality of life of children and adults with XLH treated with traditional treatment in Spain. Results showed that children had moderate problems, but adults reported moderate-to-severe problems in walking and performing their usual activities and self-care. Pain and anxiety and/or depression were very frequent. There were important differences with the general Spanish population. Moreover, we also found that XLH is associated to high healthcare cost and even higher socioeconomic cost. Our results highlight the need of improving the treatment of XLH.

Page kidney after pediatric kidney transplantation: a case report. / Riñón de Page tras trasplante renal pediátrico: informe de un caso.

INTRODUCTION: Page kidney (PK) is a rare condition caused by parenchymal compression due to a subcapsular hematoma. Irreversible damage of the graft may occur if this condition is not recognized and treated properly. CLINICAL CASE: We describe the case of a 16-year-old man with chronic renal failure secondary to corticosteroid-resistant nephrotic syndrome (CRNS) caused by NPHS2 mutations. The patient underwent a 5th fifth living-related KT. The graft was placed intraperitoneally and reperfused well without complications. On the 4th postoperative day his labs demonstrated raising creatinine associated with refractory hypertension, gross hematuria and anemia. Urgent ultrasound revealed a subcapsular hematoma with signs of parenchymal compression. PK phenomenon was suspected and urgent surgical intervention decided. COMMENTS: PK is a rare but an emergence potentially treatable and reversible complication after pediatric KT. Early diagnosis based on clinical suspicion and suggestive imaging are the key points for a favorable outcome.

INTRODUCCION: El riñón de Page (RP) es una enfermedad rara provocada por compresión parenquimatosa debido a un hematoma subcapsular. El injerto puede sufrir daños irreversibles si la enfermedad no se reconoce y se trata de forma adecuada. CASO CLINICO: Describimos el caso de un varón de 16 años con fallo renal crónico secundario a síndrome nefrótico corticorresistente (SNCR) provocado por mutaciones del gen NPHS2. El paciente se somete a un quinto TR de donante vivo. El injerto se coloca en posición intraperitoneal, con una adecuada reperfusión, sin complicaciones. Al cuarto día postoperatorio, sus análisis revelan una subida de la creatinina asociada a hipertensión refractaria, hematuria macroscópica y anemia. La ecografía de urgencia revela hematoma subcapsular con signos de compresión parenquimatosa. Se sospecha RP y se decide intervención quirúrgica de urgencia. COMENTARIOS: El RP es una complicación rara y urgente, aunque a su vez tratable y reversible, tras TR pediátrico. El diagnóstico precoz basado en la sospecha clínica y las imágenes son claves a la hora de conseguir un resultado favorable.

Riñón de Page tras trasplante renal pediátrico: informe de un caso / Page kidney after pediatric kidney transplantation: a case report

Introducción: El riñón de Page (RP) es una enfermedad rara provocada por compresión parenquimatosa debido a un hematoma subcapsular. El injerto puede sufrir daños irreversibles si la enfermedad no se reconoce y se trata de forma adecuada.Caso clínico: Describimos el caso de un varón de 16 años con fallo renal crónico secundario a síndrome nefrótico corticorresistente (SNCR) provocado por mutaciones del gen NPHS2. El paciente se somete a un quinto TR de donante vivo. El injerto se coloca en posición intraperitoneal, con una adecuada reperfusión, sin complicaciones. Alcuarto día postoperatorio, sus análisis revelan una subida de la creatininaasociada a hipertensión refractaria, hematuria macroscópica y anemia.La ecografía de urgencia revela hematoma subcapsular con signos de compresión parenquimatosa. Se sospecha RP y se decide intervenciónquirúrgica de urgencia. Comentarios: El RP es una complicación rara y urgente, aunque a su vez tratable y reversible, tras TR pediátrico. El diagnóstico precoz basado en la sospecha clínica y las imágenes son claves a la hora de conseguir un resultado favorable.

Introduction: Page kidney (PK) is a rare condition caused by parenchymal compression due to a subcapsular hematoma. Irreversible damage of the graft may occur if this condition is not recognized and treated properly.Clinical case: We describe the case of a 16-year-old man withchronic renal failure secondary to corticosteroid-resistant nephroticsyndrome (CRNS) caused by NPHS2 mutations. The patient underwent a 5th fifth living-related KT. The graft was placed intraperitoneallyand reperfused well without complications. On the 4 th postoperativeday his labs demonstrated raising creatinine associated with refractoryhypertension, gross hematuria and anemia. Urgent ultrasound revealeda subcapsular hematoma with signs of parenchymal compression. PKphenomenon was suspected and urgent surgical intervention decided.Comments: PK is a rare but an emergence potentially treatableand reversible complication after pediatric KT. Early diagnosis basedon clinical suspicion and suggestive imaging are the key points for afavorable outcome.

Outcome of kidney transplantation from young pediatric donors (aged less than 6 years) to young size-matched recipients.

INTRODUCTION: Pediatric donation is underutilized because of presumed increased risk of vascular thrombosis (VT) and graft loss. Using young pediatric donors (YPDs) for young pediatric recipients (YPRs) is suggested to be even at greater risk and therefore precluded in many centers. The aim of this study was to analyze the outcome of kidney transplantation (KT) from YPD to age-matched YPR. PATIENT AND METHODS: A retrospective study of 118 pediatric KT performed between January 2007-July 2017. The authors identified KT with YPD (considered as those aged <6 years) and age-matched YPR. Organ allocation was performed based on the best paired size (YPR for YPR). Data were collected regarding donor and recipient characteristics, surgical and urological complications, graft loss, and outcomes. RESULTS: Forty cases of YPD to age-matched YPR were identified (33.89% of the cohort). Mean recipient and donor age were 2.9 years (SD 1.68) and 2.24 years (SD 1.5), respectively. Mean recipient and donor weight were 12.7 kg (SD 4.1) and 13.7 kg (SD 4.15), respectively. Thirty of those young recipients (75%) weighed <15 kg. The most frequent primary renal disease was the congenital nephrotic syndrome. Nine out of 40 patients (22.5%) had received a previous KT before. Three received a combined liver-KT. Eight (20%) were classified as high immunological risk and 19 (47.5%) as high thrombotic risk. All allografts were implanted extraperitoneally and anastomosed to the iliac vessels. Major complications requiring reintervention occurred in seven patients (17.5%): three VT, three bleeding episodes, and one ureteral necrosis. Remarkably, only one surgical complication (VT) resulted in graft loss. Regarding long-term urological complications, four patients (10%) all with obstructive uropathy-developed vesicoureteral reflux to the graft. Actuarial graft survival at 1,5, and 10 years in the YPD to age-matched YPR cohort was 83% -78% -78%, respectively. Mean follow-up was 3.6 years (SD 3.2) (r = 7-10). Over time, eight patients lost their graft, not related to surgical factors in seven out of eight cases. CONCLUSION: The authors suggest that KT using YPD for age-match YPR yields good results in expert centers, even in high-risk patients and is associated with good graft survival. In this series, surgical complications were rarely related to graft loss.

Establishment of urinary exosome-like vesicles isolation protocol for FHHNC patients and evaluation of different exosomal RNA extraction methods.

BACKGROUND: Molecular and cellular pathophysiological events occurring in the majority of rare kidney diseases remain to be elucidated. Familial hypomagnesemia with hypercalciuria and nephrocalcinosis (FHHNC) is a rare autosomal recessive disorder caused by mutations in either CLDN16 or CLDN19 genes. This disease is characterized by massive urinary wasting of magnesium and calcium, osmosis deregulation and polyuria. Patients with p.G20D homozygous mutation in CLDN19 gene exhibit different progression to kidney failure suggesting that beyond the pathogenic mutation itself, other molecular events are favoring disease progression. Due to the fact that biopsy is not clinically indicated in these patients, urinary exosome-like vesicles (uEVs) can be envisioned as a valuable non-invasive source of information of events occurring in the kidney. Exosome research has increased notably to identify novel disease biomarkers but there is no consensus standardized protocols for uEVs isolation in patients with polyuria. For this reason, this work was aimed to evaluate and refine different uEVs isolation methods based on differential centrifugation, the gold standard method. RESULTS: Characterization by NTA, cryo-TEM and immunoblotting techniques identified the most appropriate protocol to obtain the highest yield and purest uEVs enriched fraction possible from urine control samples and FHHNC patients. Moreover, we tested five different RNA extraction methods and evaluated the miRNA expression pattern by qRT-PCR. CONCLUSIONS: In summary, we have standardized the conditions to proceed with the identification of differentially expressed miRNAs in uEVs of FHHNC patients, or other renal diseases characterized by polyuria.

Is donor age 6 years or less related to increased risk of surgical complications in pediatric kidney transplantation?

INTRODUCTION: Despite the widespread organ shortage dilemma, there is hesitancy regarding utilization of young donors (aged ≤6 years) because previous reports have suggested that this is associated with an increased risk of surgical complications and graft loss. OBJECTIVE: The aim of this study was to determine if donor age ≤6 years is related to increased risk of surgical complications or allograft loss in pediatric kidney transplantation (KT). STUDY DESIGN: A retrospective study of pediatric kidney transplants (KT) undertaken between January 2000 and July 2015. The incidence of surgical and urological complications, and allograft loss were analyzed and compared between donors aged ≤6 years (Group 1) and donors aged >6 years (Group 2). RESULTS: A total of 171 pediatric KTs were performed at the current center during the study period. Twenty-eight patients were excluded; as a result, the study comprised 143 patients: 60 (Group 1) and 83 (Group 2). Mean recipient weight was 17 kg (SD 9.7; range 3.2-47) in Group 1 and 38.2 kg (SD 15.3; range 7.8-73) in Group 2. Despite a significantly higher proportion of risk factors in Group 1, no significant between-group differences were observed in terms of: surgical complications (OR 0.4; range 0.1-1.2), early urological complications (OR 2.2; range 0.4-11), late urological complications (OR 0.3; range 0.8-1.4), lymphoceles (OR 6.2; range 0.7-51.7) and allograft loss (OR 1.5; range 0.7-3.1, summary Table). Graft survival at 1 and 5 years was: 81% and 70% (Group 1) and 92% and 79% (Group 2), respectively (P = 0.093). Mean follow-up was 90.13 ± 49.7 months. DISCUSSION: The main finding of this retrospective study was that pediatric donor kidneys from donors aged ≤6 years could safely be used in pediatric recipients without an increased risk of surgical and urological complications or graft loss. Nevertheless, KT with small donor kidneys is challenging and should be performed at experienced pediatric centers. CONCLUSION: In line with these results, the outcomes of KT using donors aged ≤6 years were encouraging and similar to those obtained with older donors. Thus, this study supported using kidney grafts from young donors, given the organ shortage and potential high mortality risk while awaiting KT.

Improvement of refractory pruritus after lipoprotein-apheresis in arthrogryposis-renal failure-cholestasis syndrome.

Accumulation of bile acids can lead to invalidating pruritus in cholestatic patients. Few reports exist on the influence of lipoprotein-apheresis (LA) on plasma level of total bile acids (tBA). We report of significant decrease in tBA levels and drastic improvement of pruritus in a 5-year-old girl with arthrogryposis-renal failure-cholestasis syndrome. We present LA as a suitable rescue treatment option in therapy-refractory cholestasis-associated pruritus, at least as bridge until a long-term solution such as entero-biliary anastomosis or transplantation is possible.

Considerable variations in growth hormone policy and prescription in paediatric end-stage renal disease across European countries-a report from the ESPN/ERA-EDTA registry.

BACKGROUND: Growth retardation in paediatric end-stage renal disease (ESRD) has a serious impact on adult life. It is potentially treatable with recombinant growth hormone (rGH). In this study, we aimed to quantify the variation in rGH policies and actual provided care in these patients across Europe. METHODS: Renal registry representatives of 38 European countries received a structured questionnaire on rGH policy. Cross-sectional data on height and actual use of rGH on children with ESRD aged <18 years were retrieved from the ESPN/ERA-EDTA Registry. RESULTS: In 21 (75%) of 28 responding countries, rGH is reimbursed for children with ESRD. The specific conditions for reimbursement (minimum age, maximum age and chronic kidney disease stage) vary considerably. Mean height standard deviation scores (SDS) at renal replacement therapy (RRT) [95% confidence interval (CI)] were significantly higher in countries where rGH was reimbursed -1.80 (-2.06; -1.53) compared with countries in which it was not reimbursed [-2.34 (-2.49;-2.18), P < 0.001]. Comparison of the mean height SDS at onset of RRT and final height SDS yielded similar results. Among the 13 countries for which both data on actual rGH use between 2007 and 2011 and data from the questionnaire were available, 30.1% of dialysis and 42.3% of transplanted patients had a short stature, while only 24.1 and 7.6% of those short children used rGH, respectively. CONCLUSION: Reimbursement of rGH associates with a less compromised final stature of ESRD children. In many countries with full rGH reimbursement, the actual rGH prescription in growth-retarded ESRD children is low and obviously more determined by the doctor's and patients' attitude towards rGH therapy than by financial hurdles.

Desarrollo de la Nefrología Pediátrica en el Hospital Universitario Vall d´Hebron / Development of pediatric nephrolgy in the University Hospital Vall d´Hebron

El desarrollo de la nefrología pediátrica ha sido paralelo al significativo aumento de la superviciencia de niños y adolescentes con enfermedad renal en las últimas décadas. El Servicio de Nefrología Pediátrica del Hospital Universitario Vall d´Hebron (HUVH( es el servicio terciario de referencia de la subespecialidad en la red sanitaria pública de Catalunya e Islas Baleares. Los hitos más representativos en su historia han sido los siguientes: 1970 primera hemodiálisis (HD) pediátrica del Estado, 1981 primer transplante de riñon (TxR) pediátrico, 1994 primer traspaltne hepato-renal del Estado y 2008 acreditación como unidad de referncia CSUR para TxR pediátrico. En la actualidad, la actividad clínica del servicio se focaliza en los programs de TxR, diálisis, enfermedad renal crónica (ERC) y enfermedades renales minoritarias del niño y adolescente. Asimsimo, el servicio realiza una intensa actividad docente e investigadora en el campo de la subespecialidad. Los principales retos actuales son los progrmas de cronicidad específicos, y la transferencia protocolizada de los adolescentes a los servicios de nefrología de adultos (AU)

Pediatric Nephrology discipline has been developed simultaneously with the remarkable improvement of life expectancy occurred in children and adolescentes with renal disease during the past decades. The Pediatric Nephrology Service of the Universitary Hospital Vall d´Hebron (HUVH) is the major service of the public health system for Catalunya and Balear Islands in the subspeciality. The most representative milestones of the Sevice were: first pediatric hemodialisis (HD) in Spain in 1970; first peditric kidney transplant (KTx) in1981; first combined liver and kidney transplant in the country in 1994, and acreditation as reference center CSUR for pediatric KTx in 2008. Currently, clinical activity is mostly focused on KTx, dialysis, chronic kidney disease, and rare renal diseases in children and adolescents. Further, the service is active in teaching and research in the field. Major current chalenges are the development of chronicity programmes and protocolized transfer of care of adolescents from pediatric to adult Nephrology Services (AU)

Hypercalciuria is the main renal abnormality finding in Human Immunodeficiency Virus-infected children in Venezuela.

Kidney involvement in children with Human Immunodeficiency Virus (HIV) infection is increasing in prevalence in parallel with the longer survival of HIV-infected patients and the side-effects of new antiretroviral drugs. However, there are only a few reports describing renal tubular disorders in HIV+ children. This is a cross-sectional, case series study evaluating kidney disease in 26 Venezuelan HIV-infected children. The study cohort consisted of 15 girls and 11 boys, with a median age of 5.9 years (25-75th percentile: 3.6-7.8), who had been treated with antiretrovirals for 2.8 +/- 0.4 years, Overall, the patients were short for their age and gender (Z-height: -3.1; 25-75th percentile: -4.94 to -1.98), and 15 showed signs of mild to moderate malnutrition. All of the children had a normal estimated glomerular filtration rate (136 +/- 22.6 ml/min/1.73 m2), and glomerular involvement was only observed in one patient with isolated proteinuria. None had nephromegaly. In contrast, tubular disorders were commonly found. Hypercalciuria was detected in 16 of the patients (UCa/Cr = 0.28; 25-75th percentile: 0.17-0.54 mg/mg), with five of these showing crystalluria. Eight children showed hyperchloremia, and three had frank metabolic acidosis. Kidney stones were absent in all, but one boy had bilateral medullary nephrocalcinosis. Conclusion, in Venezuelan children, HIV infection per se, or its specific treatment, was commonly associated with renal tubular dysfunction, especially hypercalciuria and acidosis, potentially leading to nephrocalcinosis and growth impairment. We recommend renal tubular evaluation during the follow-up of children with HIV infection.

[Long-term prognosis of childhood IgA nephropathy in adult life]. / Pronóstico en la vida adulta de la nefropatía IgA diagnosticada en la edad pediátrica.

BACKGROUND: To evaluate long-term prognosis in a group of children with IgA nephropathy and to analyse which clinical factors were associated with progression to chronic renal failure in adulthood. PATIENTS AND METHOD: Retrospective study. 58 young adults with IgA nephropathy diagnosed at 10.6(SD 2.9) years old and studied after a follow-up of 11.8 (SD 2.9) years. RESULTS: Relapses of macroscopic hematuria and proteinuria were the most frequent symptoms at onset (75.9%). In 25.9% of patients high plasmatic IgA levels were also detected. Most cases had grade I (44.8%)or grade II (44.8%) histological lesions at diagnosis. At the last control, clinical remision was observed in 21 patients (36.2%) and 50% of the whole group remained with abnormal urine. 8 patients(13.8%) reached terminal renal failure. Mean renal survival (defined as glomerular filtration rate above 50 ml/min/1.73 m2)was 100, 93.3 and 81.1% at 5, 10 and 15 years of evolution, respectively. CONCLUSIONS: About 14% of children with IgA nephropathy had long-term renal bad prognosis. Hypertension at onset, plasma creatinine elevation and proteinuria during adolescence were significant risk factors associated with chronic renal failure during adulthood. Minimal lesions at IgA nephropathy diagnosis in children did not exclude long-term poor prognosis.

Acute and chronic effects of cisplatin therapy on renal magnesium homeostasis.

Although the acute renal toxicity of cisplatin has been well documented, long-term follow-up studies in cisplatin-treated children are scanty. We have evaluated the incidence and characteristics of both acute and chronic nephrotoxicity in 22 children (median age 8 years) treated with cisplatin as part of different chemotherapeutic protocols. All patients exhibited a significant and progressive decrease in plasma magnesium (Mg) values soon after cisplatin administration. Magnesiuria also increased immediately after therapy. Hypomagnesemia (plasma Mg < 1.4 mg/dl) occurred in 10 patients and it was dose-dependent. Minimal and mean cumulated doses inducing hypomagnesemia were 300 and 500 mg/m2, respectively. In 18 children we followed renal function prospectively for a mean time of 2.3 years after arrest of cisplatin therapy. Chronic hypomagnesemia and moderate elevation of plasma creatinine were observed in 6 children, hypocalciuria in 5 children, and hypokalemia in 1 child. Presence of hypomagnesemia was unrelated to the total dose received or the time elapsed since cisplatin therapy. Renal function studies, performed in the 6 children with chronic hypomagnesemia, revealed different degrees of impairment in Mg reabsorption. The functional characteristics of chronic cisplatin nephrotoxicity found in the present series-contrary to prior reports-are not comparable to those present in the inherited Gitelman's syndrome.

Renal magnesium handling in infants and children.

Renal handling of magnesium (Mg) has been incompletely studied during infancy and childhood due to the difficulty, until recently, of measuring the diffusible fraction of plasma Mg. In the present investigation this methodology has been used to assess Mg homeostasis in 45 healthy infants, aged 1 to 12 months, and in 63 healthy children, aged 1 to 15 years. When compared to children, infants had significantly higher plasma values (mean +/- SD) for both total (0.76 +/- 0.08 versus 0.70 +/- 0.06 mmol l-1; p < 0.001) and ultrafilterable Mg (0.51 +/- 0.07 versus 0.49 +/- 0.04 mmol l-1; p < 0.05). No significant correlations were present between values of plasma Mg and plasma concentrations of calcium, creatinine, total protein or albumin. The ratio Umg/Ucr, calculated in the second morning urine (median, 3rd-97th centiles), was also significantly higher during infancy (0.023, 0.009-0.07 versus 0.015, 0.006-0.04; p < 0.001). On the contrary, fractional excretion of Mg (median, 3rd-97th centiles) was identical in both age groups and did not correlate significantly with age (infants: 3.2, 1.0-7.8%, children 3.4, 1.6-8.1%; p = NS). During a Mg infusion, carried out in six children, we could establish an approximative value for renal Mg threshold (plasma ultrafilterable Mg = 0.50 mmol l-1) close to that found in adults. These results indicate that no functional immaturity is present during infancy for renal tubular reabsorption of Mg and that the high Umg/Ucr ratio observed in this age group is a phenomenon not dependent on a higher urinary Mg excretion but probably related to a lower urinary creatinine excretion per unit of lean body mass.

Renal tubular handling of potassium in children with insulin-dependent diabetes mellitus.

To clarify the mechanism by which renal potassium (K) excretion is reduced in children with insulin-dependent diabetes mellitus, we studied two groups of patients: (A) at diagnosis and (B) after at least 1 year of follow-up. Group A (15 children) was studied twice: on the day of admission and after 1 month of insulin therapy. On admission, urinary K excretion, fractional K excretion, and transtubular K concentration gradient (TTKG) were significantly decreased, but became normal after extended insulin therapy. TTKG was inversely correlated with blood glucose (P < 0.001) and hemoglobin A1c (HbA1c, P < 0.001). Group B (73 children with a mean follow-up of 54 +/- 36 months) was subdivided according to the TTKG: 30 patients had a low TTKG < 4.0 (median 3.2) and 43 patients had a normal TTKG > or = 4.0 (median 5.2). Patients had a low TTKG and those with a normal TTKG had an identical duration of follow-up and similar values for plasma renin activity, aldosterone concentration, calciuria, magnesiuria, albumin excretion rate, and creatinine clearance. However, those with a low TTKG had significantly higher blood HbA1c levels, urine volume, and glucosuria. Logistic regression analysis showed that the only independent variables predicting a low TTKG were blood HbA1c and glucosuria (P < 0.001). These data confirm that a reduced renal K excretion is a characteristic feature of diabetic children; this is reversible with appropriate insulin therapy, largely depends on the metabolic control of the disease, and, specifically, on the degree of hyperglycemia and/or glucosuria.

Magnesium homeostasis in premature and full-term neonates.

Renal handling of magnesium (Mg) has not been comprehensively studied in the newborn period due to the difficulty, until recently, of measuring the diffusible fraction of plasma Mg (UfMg). In the present study this methodology was used to assess Mg homeostasis in 84 newborn infants of different postconceptional age (26-42 weeks), weight (720-4,830 g) and postnatal age (1-72 days). Very premature infants (postconceptional age less than 35 weeks) had significantly higher values of plasma Mg than mature newborn infants. Plasma Mg related inversely to postconceptional age, weight, plasma total protein and plasma calcium, and directly to plasma potassium. Stepwise multiple regression analysis revealed that postconceptional age was the unique factor contributing to variations in plasma Mg. Plasma values of UfMg were the same in preterm as in term infants but, when expressed as a fraction of total plasma Mg (UfMg/Mg), they were significantly lower in very preterm infants. Fractional excretion of Mg and the ratio of urine Mg to urine creatinine did not vary as a function of postconceptional age. These results indicate that plasma UfMg is kept constant at different gestational ages despite variations in total plasma Mg; furthermore, no functional immaturity is present for renal tubular reabsorption of Mg, even in very low birth weight infants.

Chloride deficiency as a presentation or complication of cystic fibrosis.

Thirteen children with cystic fibrosis (CF), aged 1.5 months-15 years, had 18 episodes of hypochloraemia and metabolic alkalosis over the period 1983-1991. Five patients were not known to have CF prior to developing these electrolyte disturbances. There were two distinct clinical presentations: 5 patients had an acute isolated picture of heat exhaustion while 8 patients (all infants) had a more chronic course associated with failure to thrive. Many episodes were not associated with particularly high environmental temperatures, although most occurred during the summer and early autumn months. Serum electrolytes should be assessed regularly in children with CF, and this diagnosis should be considered in any infant presenting with unexplained hypochloraemic metabolic alkalosis.