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Bernd Hoppe

Publications and source records attributed to Bernd Hoppe.

26 records · Page 2Linked to original sources
PubMed2003

Diagnostic and therapeutic approaches in patients with secondary hyperoxaluria.

Secondary hyperoxaluria is due either to increased intestinal oxalate absorption or to excessive dietary oxalate intake. Certain intestinal diseases like short bowel syndrome, chronic inflammatory bowel disease or cystic fibrosis and other malabsorption syndromes are known to increase the risk of secondary hyperoxaluria. Although the urinary oxalate excretion is usually lower than in primary hyperoxaluria, it may still lead to significant morbidity by recurrent urolithiasis or progressive nephrocalcinosis. A clear distinction between primary and secondary hyperoxalurias is important. As correct classification may be difficult, appropriate diagnostic tools are needed to delineate the metabolic background as a basis for optimal treatment. We developed an individual approach for the evaluation of patients with suspected secondary hyperoxaluria. First, 24 h urines are examined repeatedly for lithogenic (e.g. calcium, oxalate, uric acid) and stone-inhibitory (e.g. citrate, magnesium) substances, and the patients are asked to fill in a dietary survey form. Urinary saturation is calculated using the computer based program EQUIL2, and the BONN-Risk-index is determined. The measurement of plasma oxalate and of urinary glycolate helps to distinguish between primary and secondary hyperoxalurias. If secondary hyperoxaluria is suspected, the stool is examined for Oxalobacter formigenes, an intestinal oxalate degrading bacterium, as lack or absence may lead to increased intestinal oxalate absorption. The last diagnostic step is to study the intestinal oxalate absorption using [13C2]oxalate. Depending on the results, various therapeutic options are available: 1) a diet low in oxalate, but normal or high in calcium, 2) a high fluid intake (>1.5 L/m2/d), 3) medications to increase the urinary solubility, 4) specific therapeutic measures in patients with malabsorption syndromes, depending on the underlying pathology, and 5) intestinal recolonization of Oxalobacter formigenes or the treatment with other oxalate degrading bacteria.

Humans↗
PubMed2003

A United States survey on diagnosis, treatment, and outcome of primary hyperoxaluria.

Primary hyperoxaluria (PH) is a heterogeneous disease with a variable age of onset and a variable progression into kidney failure. Early diagnosis is mandatory to avoid the damaging effects of systemic calcium oxalate deposition. In 1997, we initiated a nationwide survey of American nephrologists to ascertain epidemiological data and current practices. PH was reported in only 102 patients, with PH I in 79 and PH II in 9; 14 patients were not classified. Most patients were Caucasian (84%). Main symptoms at diagnosis were urolithiasis (54.4%) and nephrocalcinosis (30%). A significant delay of diagnosis was seen in 42% of patients and 30% of patients were diagnosed only at end-stage renal disease (ESRD). Diagnosis was usually based on history and urinary oxalate excretion. Glycolate and l-glyceric acid excretion were rarely determined. To determine the enzyme defect, a liver biopsy was performed in 40%. Even at ESRD, only 56% of patients received an adequate diagnostic work-up. Half of the patients showed 'good' or 'fair' pyridoxine sensitivity. In addition to B(6), most patients received either citrate or orthophosphate. Kidney transplantation (KTx) failed in 19 of 32 transplants ( n=27 patients) and was due to recurrent oxalosis in 8 transplants. Liver Tx was performed after KTx in 5 patients (1 patient died). Combined liver-kidney Tx in 21 patients (in 9 patients after failure of KTx) achieved good organ function in 13 patients; 7 patients, however, died shortly after transplantation. In conclusion, the time between first symptom and diagnosis of PH must be minimized, and the diagnostic procedures have to be improved. The cases of unclassified hyperoxaluria suggest the possibility of additional type(s) of PH. As isolated KTx failed in 59% of patients, combined liver-kidney Tx seems to be the better choice in place of isolated KTx as the primary transplant procedure.

Adolescent↗
PubMed2003

Urinary NAG in children with urolithiasis, nephrocalcinosis, or risk of urolithiasis.

A crucial role for cell-crystal interactions in the development of urolithiasis (UL) and nephrocalcinosis (NC) was previously observed in experiments with different cell lines mimicking renal epithelial cells. It was found that such cell-crystal interactions lead to tubular damage and/or or dysfunction. To find further proof for these observations, we measured the urinary N-acetyl-beta- d-glucosaminidase (NAG) excretion, a marker of proximal tubular damage, in children with UL or NC and in children with an increased risk of UL. We enrolled 142 children aged 4-16 years (mean 9.67+/-3.40 years), with 50 children having UL, 30 children with a history of UL (ULH), 20 patients with NC, 34 children with secondary hyperoxaluria (HyOx), and 8 children with idiopathic hypercalciuria (HC). Normal urinary NAG/Cr values were determined in a group of 70 healthy children aged 4-16 years (mean 10.06+/-3.97 years). The urinary NAG activity was measured using a colorimetric method and the results were expressed as molar creatinine (Cr) ratios. The highest median NAG/Cr ratios were found in children with UL plus hematuria (0.72 U/mM) and in children with UL (0.67 U/mM) or NC (0.48 U/mM), which were all significantly higher than those in controls (0.28 U/mmol, P<0.001 and P<0.05). The NAG/Cr ratios were increased above the upper normal reference interval of 0.63 U/mM (95th percentile) in 28 of 50 (56%) children with UL and in 9 of 20 (45%) children with NC. Although the ULH group also had significantly higher median NAG/Cr ratios (0.36 U/mM) compared with controls, the NAG/Cr ratio was only elevated in 4 of 30 (13%) patients. NAG values in children with secondary HyOx or HC were not different from controls. No correlation was found between the NAG/Cr ratios and the urinary excretion of oxalate or calcium. In conclusion, UL or NC may result in proximal tubular injury, which is rather the consequence of disease activity and of the mechanical influence of calculi, than of the metabolic background. The mechanism of cell damage in these conditions however, seems to be complex. Neither HyOx nor HC alone were sufficient to induce severe tubular damage expressed as an increase in NAG excretion in our patients.

Acetylglucosaminidase↗
PubMed2003

Hypocitraturia is one of the major risk factors for nephrocalcinosis in very low birth weight (VLBW) infants.

BACKGROUND: Very low birth weight (VLBW) infants are at risk to develop nephrocalcinosis (NC). NC may result from spontaneous or therapy-induced imbalance between promoters and inhibitors of crystallization in the urine. However, data on "normal" urinary excretions of these parameters in VLBW infants are sparse. Therefore, we prospectively examined the urinary excretion of calcium, oxalate, uric acid, and citrate in VLBW infants during the first 8 weeks of life. METHODS: Urine samples were collected once weekly in 124 VLBW infants. NC appeared in 16 infants, whose data were separately analyzed. The remaining 108 infants were divided into subgroups: A, <1000 g (N = 53); and B, 1000 to 1500 g (N = 55). Random urine samples were analyzed and the results were expressed as molar creatinine ratios. Calcium/citrate and oxalate/citrate expressed the risk for calcium oxalate crystallization. RESULTS: In group A, citrate excretion was lower at weeks 2 to 5 and 7; calcium/citrate was higher in weeks 2, 4, and 7; oxalate/citrate was higher in weeks 3, 4, 7, and 8; and calcium/creatinine ratio was higher in week 4 (P < 0.05). Citrate/creatinine ratios were low in nine infants with NC. Oxalate/creatinine and calcium/creatinine were elevated in five and calcium/citrate was increased in nine infants with NC. CONCLUSION: Hypocitraturia is a major risk factor for NC in VLBW infants, especially in those <1000 g. The urinary excretions in VLBW infants seem to depend on birth weight, age, and clinical condition. Hence, supplementation with alkali citrate may have a beneficial effect in the prevention of NC.

Calcium↗
PubMed2002

Posttransplant lymphoproliferative disease in a child: clinical and molecular characterization.

We report a 12-year-old girl suffering from end-stage renal disease due to focal-segmental sclerosis and retardation of statomotoric and mental development of unknown origin. Renal transplantation (TX) was performed 7 months after initiation of peritoneal dialysis at the age of 11 years. Immunosuppressive therapy included cyclosporine A, mycophenolate mofetil and methylprednisolone. The patient developed spiking fever up to 40 degrees C without signs of infection 10 months after TX. Kidney function remained stable but ultrasound examination and CT-scan showed hypodense masses within both liver and spleen. Epstein-Barr virus (EBV) polymerase chain reaction (PCR) results with a high number of copies (20 x 10(6) copies/ml blood) against the background of a previous EBV infection (IgG positive, IgM negative) made the diagnosis of EBV-reactivation likely. Splenectomy was performed. Examination of the spleen showed EBV-associated polymorphic posttransplant lymphoproliferative disease (PTLD) with predominant B cell proliferation and monoclonal VH3-rearrangement of the IgG heavy chain locus. Therapy with acyclovir was introduced and immunosuppression was reduced. No rejection episode occurred. Body temperature normalized and the patient recovered over a 3-month period. EBV-PCR in plasma was negative (0.02 x 10(6) copies/ml blood) 12 weeks after reduction of immunosuppression. The liver masses completely resolved after 27 months. After a total follow-up of 36 months the child remains in good health.

Acyclovir↗
PubMed2002

Nephrocalcinosis in preterm infants: a single center experience.

The risk of nephrocalcinosis in preterm infants is considerable, but conflicting numbers are given for the actual incidence (10-65%). Furosemide induced hypercalciuria is said to be the main risk factor. We examined retrospectively the incidence, causes and outcome of nephrocalcinosis in preterm infants born in our hospital from 1988 to 1998 ( n=2190). An abnormal renal echogenicity or nephrocalcinosis was seen in 31 infants (29.7+/-3.3 weeks gestational age; 1307+/-690 g birth weight). Nephrocalcinosis was diagnosed in 16, hyperechoic kidneys (HK) in 10 and Tamm-Horsfall kidneys in 5 infants. Main risk factors were low gestation age and birth weight, length of hospitalization, variations in acid-base status, length of assistant ventilation and hypercalciuria at diagnosis. The incidence of nephrocalcinosis was 0.73% [1.7% for low birth weight infants (VLBW)]. Taking the cases of nephrocalcinosis and HK together, incidence was calculated to be 1.2% overall and 2.5% for VLBW infants, but increased to 7% in 1998. The follow-up showed persisting nephrocalcinosis or hyperechoic kidneys in 8/26 preterm infants. In conclusion, the incidence of nephrocalcinosis was lower in our population than is usually reported. The numbers have, however, increased over the past few years. From the follow-up it was obvious that long-term observation of preterm infants is necessary and that complications might arise in the long run.

Follow-Up Studies↗