Acyclovir-induced acute tubulo-interstitial nephritis

Two patients with presumed herpes simplex encephalitis developed severe non-oliguric acute renal failure shortly after acyclovir infusions. Renal function returned to normal in less than 3 weeks after discontinuation of acyclovir. Renal biopsies done during the acute phase demonstrated interstitial oedema, eosinophils and cellular aggregates in both and granulomata in the second case suggesting acyclovir-induced hypersensitivity interstitial nephritis.     

A case of acute tubulo-interstitial nephritis and uveitis syndrome

We report herein the case of a 14-year-old female who has acute tubulo-interstitial nephritis (AIN) associated with bilateral diffuse uveitis. She was admitted for the evaluation of "proteinuria", following general fatigue and weight loss about 2 weeks ago. Her laboratory data showed mild anemia, hyper gamma-globulinemia, mild proteinuria, and the reduced glomerular filtration rate with the increased urinary excretion of beta 2-microglobulin. The histological examination obtained by renal biopsy showed mild edema and diffuse infiltration of mononuclear cells in interstitium without any glomerular or vascular abnormalities, which were compatible with AIN. As for the etiology of AIN, clinical investigations could not reveal any specific causes, such as bacterial and viral infections, drugs and systemic diseases. About 4 months after the onset of nephritis, she also became to suffer from bilateral diffuse uveitis. Therefore, the diagnosis of the acute tubulo-interstitial nephritis and uveitis syndrome (TINU syndrome) (Vanhaesebrouck et al., 1985) could be confirmed. In her clinical course, it was noteworthy that uveitis relapsed frequently in spite of systemic administration of prednisolone, and it took two years until uveitis cured, whereas the AIN subsided spontaneously prior to the specific treatment. In this case, characteristic findings of granulomatous uveitis was closely similar to those of sarcoidosis, which has been rarely reported in TINU syndrome. In this respect, the involvement of immune processes, especially cell-mediated, was suggested as the possible pathogenesis in this case.     

A case report of chronic tubulo-interstitial nephritis]

We report a case of 10-year-old boy with chronic tubulo-interstitial nephritis (TIN). He had febrile convulsion and received sodium valproate (VPA) treatment. 18 months later, he had developed Fanconi syndrome. On admission, he also had evidence of tubular and glomerular dysfunction. Renal biopsy revealed interstitial nephritis with linear tubular-basement-membrane deposition of IgG and C3 and dominant infiltration of CD4 positive cells in interstitium. Although there is not a positive proof of the etiology in the relationship between TIN and VPA, it is likely that VPA is a possible cause of chronic TIN from his past history.     

Role of iron in the tubulo-interstitial injury in nephrotoxic serum nephritis

We studied the possibility that tubule fluid iron could be involved in the pathogenesis of the tubulo-interstitial injury associated with primary glomerular disease. Tubule fluid iron is determined by the magnitude of the glomerular leak for transferrin and the iron saturation of transferrin. To minimize tubule fluid iron in an experimental model of glomerulonephritis, iron deficiency was induced in rats prior to the induction of nephrotoxic serum nephritis. Iron deficiency did not effect the development of glomerular disease as determined by proteinuria, but had a marked effect on preventing the development of tubulo-interstitial disease and renal functional deterioration. There was also a strong correlation between the amount of functional deterioration and extent of tubulo-interstitial disease and urinary iron excretion in both the control and iron deficient animals. It is proposed that injury results from iron being dissociated from transferrin at the more acid pH of the tubule fluid. Iron, a transition element, is able to catalyze the Haber-Weiss reaction with the formation of free hydroxyl radicals which causes renal tubule cell injury. This tubulo-interstitial injury is the major determinate of progressive renal functional deterioration in this experimental model of glomerulonephritis.     

Acute tubulo-interstitial nephritis and uveitis syndrome (TINU syndrome)

Acute renal failure due to tubulo-interstitial nephritis developed in a 15-year-old girl. The disease was accompanied by uveitis and an inflammatory syndrome, consisting of a markedly increased erythrocyte sedimentation rate and high serum gamma globulin levels. The nephropathy as well as the inflammatory syndrome subsided spontaneously. A topical antiphlogistic treatment healed the ocular disease, which has not relapsed so far. The association of acute tubulo-interstitial nephritis and acute uveitis observed in several patients has led to the identification of a specific syndrome with a very particular symptomatology and course, the so-called TINU syndrome, the interest of which resides in the predictability of the complete reversibility of the nephropathy either spontaneously or after steroid treatment, contrasting with the marked tendency towards relapse of the uveitis. The demonstration of circulating immune complexes in the serum during the acute phase of the illness, as in our patient, further points to the involvement of immune processes in the syndrome, but the origin and pathogenesis remain as yet unknown.     

Sarcoid tubulo-interstitial nephritis: long-term outcome and response to corticosteroid therapy

Sarcoidosis is a chronic relapsing multi-systemic disorder characterized by the development of non-caseating granulomas. Granulomatous tubulo-interstitial nephritis is an uncommon manifestation of this condition. We identified 39 patients with sarcoidosis and renal disease from a single center of whom 17 patients had biopsy-proven tubulo-interstitial nephritis. They were analyzed with respect to demographic and clinical features, including response to corticosteroids and length of follow-up. They all presented with significant renal impairment. At presentation the mean+/-s.d. estimated glomerular filtration rate (eGFR) was 26.8+/-14 ml/min by modification of diet in renal disease (MDRD) equation 7. With treatment there was a significant improvement in renal function with eGFR 49.6+/-5.2 ml/min (P<0.01) at 1 year, and 47.9+/-6.8 ml/min (P<0.05) at the last review. The median follow-up was 84 months (range 6-284 months). Patients with chronic kidney disease (CKD) 3, the mean eGFR was 38.30+/-2.4 ml/min at presentation and 60.2+/-7.4 ml/min at 1 year (P=0.02) and in CKD 4 it improved from 19+/-2 to 38+/-6.6 ml/min at 1 year (P<0.05). After the 1st year, the change in eGFR was +0.8 ml/min/year for CKD 3 and -2 ml/min/year for CKD 4 (P<0.05). Three patients ceased their therapy either due to complications or poor compliance and experienced a worsening of renal function which was then reversed on re-commencing corticosteroids. Corticosteroids are effective in advanced tubulo-interstitial nephritis due to sarcoidosis. Long-term treatment is necessary to preserve renal function and to delay the onset of end-stage renal disease.     

Acute tubulo-interstitial nephritis from candida albicans with oliguric renal failure

A patient developed candidemia after receiving steroids and antibiotics. Subsequently, acute oliguric renal failure occurred. Renal biopsy showed multiple cortical microabscesses. These contained encapsulated ovoid Candida, budding organisms, short hyphae, and polymorphs. Adjacent tubules showed disruption of the basement membrane, infiltration by polymorphs and necrosis. There was no evidence of pelvic-calyceal obstruction by bezoar. The acute renal failure was attributed to acute candidal tubulo-interstitial nephritis, and was successfully reversed with Amphotericin.     

Changes in magnesium and potassium homeostasis after conversion from a calcineurin inhibitor regimen to an mTOR inhibitor-based regimen

Background

Transplant recipients treated with calcineurin inhibitors (CNIs) frequently show hyperkalemia, metabolic acidosis, and hypomagnesemia which could be deleterious for some patients. Conversion to inhibitors of mammalian target of rapamycin (mTOR) could improve these electrolytic disturbances.

Objective

To evaluate the potassium and magnesium changes due to converting patients from CNIs to mTOR inhibitors.

Methods

Retrospective review of 138 renal transplant patients who were converted from CNIs to mTOR inhibitors over a 6-month observation period. The following parameters were determined: potassium, sodium, chloride, magnesium, urea, glucose, and creatinine in blood and urine. We also analyzed plasma bicarbonate and calculated plasma and urine anion gap and plasma osmolarity.

Results

One month after conversion, a decrease was observed in serum creatinine (1.75 ± 0.68 vs 1.61 ± 0.61 mg/dL; P = .01), plasma potassium (4.60 ± 0.52 vs 4.39 ± 0.53 mEq/L; P < .001), calculated plasma osmolarity (308.7 ± 8.5 vs 307.4 ± 8.4 mOsm/L; P < .036), fractional excretion of sodium (1.55 ± 0.69 vs 1.29 ± 0.65%; P < .003), and fractional excretion of magnesium (7.15 ± 4.08 vs 15.84 ± 3.64%; P < .001), with an increase in serum magnesium (1.77 ± 0.24 vs 1.95 ± 0.29 mg/dL; P < .001). At 3 and 6 months, these differences remained unchanged. The transtubular potassium gradient did not change.

Conclusions

We observed a decrease in serum magnesium due to renal magnesium wasting before switching from CNIs to mTOR inhibitors. After conversion, an increase in serum magnesium was observed together with a drop in the fractional excretion of this cation. A decrease in plasma potassium levels, plasma osmolarity, and fractional excretion of sodium consistent with minor aldosterone resistance was also detected after changing the immunosuppressive treatment.     

Histology of human tubulo-interstitial nephritis associated with antibodies to renal basement membranes.

Twenty-seven patients with diffuse "crescentic" glomerulonephritis (CSGN) were identified in 1,174 renal biopsies from nephritic patients. Patients were assigned to three groups on the basis of the immunofluorescent study of renal biopsy specimens and serologic findings. Group I included eight patients with antibodies to glomerular (anti-GBM) and tubular (anti-TBM) basement membranes; group II had eight patients with only anti-GBM antibodies; and group III had eleven patients with CSGN unassociated with antibodies to either GBM or TBM. Patients with anti-GBM/anti-TBM antibodies (group I) had severe tubulointerstitial (TI) nephritis, as characterized by the infiltration of polymorphonuclear leukocytes and macrophages along the TBM and peritubular vessels. In some patients, focal proliferation of epithelial cells of proximal convoluted tubules (PCT), gaps or extensive destruction of TBM, lesions in the walls of small peritubular vessels, and interstitial giant cells were also observed. Patients with anti-GBM antibodies (group II) had mild to moderate interstitial cellular infiltration and mild tubular changes. Five patients with CSGN not associated with antibodies to renal basement membranes (group III) had mild to moderate interstitial cellular infiltration and tubular changes. A sixth patient, with Wegener's disease had severe granulomatous TI lesions. The results of this study show that TI nephritis is most frequent and severe with anti-TBM antibodies are demonstrable and suggest that anti-TBM antibodies contribute to the development of TI lesions.     

Aminoglycosides and renal magnesium homeostasis in humans.

BACKGROUND: The use of aminoglycosides has been linked with hypomagnesaemia in scattered reports. The objective of the study was to measure prospectively the effect of treatment with the aminoglycoside amikacin on renal magnesium homeostasis. METHODS: Twenty-four cystic fibrosis patients (aged 9-19 years) admitted because of exacerbation of pulmonary symptoms caused by Pseudomonas aeruginosa were treated with the aminoglycoside amikacin and the cephalosporin ceftazidime for 14 days. Renal values and plasma and urinary electrolytes were measured before and at the end of the systemic anti-pseudomonal therapy. RESULTS: In the patients with cystic fibrosis, treatment with amikacin and ceftazidime did not modify plasma creatinine or urea and plasma or urinary sodium, potassium and calcium. Treatment with amikacin and ceftazidime significantly decreased both plasma total magnesium (from 0.77 (0. 74-0.81) to 0.73 (0.71-75) mmol/l; median and interquartile range) and ionized magnesium (from 0.53 (0.50-0.55) to 0.50 (0.47-0.52) mmol/l) concentration and increased fractional urinary magnesium excretion (from 0.0568 (0.0494-0.0716) to 0.0721 (0.0630-0.111)) and total urinary magnesium excretion (from 30.7 (26.5-38.0) to 38.5 (31. 5-49.0) micromol/l glomerular filtration rate). CONCLUSIONS: The present study demonstrates that systemic therapy with amikacin plus ceftazidime causes mild hypomagnesaemia secondary to renal magnesium wasting even in the absence of a significant rise in circulating creatinine and urea.     

Calcium homeostasis and bone pathology in magnesium deficient rats

Summary Calcium homeostasis and bone pathology were studied in weanling rats fed a low (70 ppm) magnesium diet for 2–21 days. The rats developed significant, progressive hypercalcemia after 6 days on the diet. The increase in blood calcium was accompanied by progressive hypoactivity of the parathyroid gland (PTG), as determined by histologic and morphometric analyses. Thus hyperactivity of the PTG could not have been responsible for the hypercalcemia observed. Histologic examination of femora and humeri from magnesium-deficient rats showed progressive subperiosteal hyperplasia, consisting of undifferentiated osteoprogenitor cells and fibrous tissue, after 7 days of deficiency. The presence of unmineralized osteoid tissue in the metaphyses indicated that mineralization was not proceeding normally. The alterations in differentiation of osteoprogenitor cells, together with the failure of mineralization, resulted in significantly lower rates of bone formation (as measured by fluorochrome labeling) in the magnesium-deficient rats. Basophilic cementing lines and inactive osteocytes in the cortices of bones from magnesium-deficient rats indicated that bone resorption was also severely reduced in magnesium deficiency. We postulate that bone magnesium depletion (66% by day 21) has a direct negative effect on osteoblastic and osteocytic activity, and may explain, in part, the decreased responsiveness of bone to parathyroid hormone (PTH) that has been observed in magnesium-deficient animals.     

Impaired renal and extrarenal potassium adaptation in old rats

Young (3 to 4 months) and old (21 to 22 months) rats were fed either a regular or high potassium (K) diet. After acute potassium chloride infusion, the fraction of infused K excreted (K efficiency) was similar in rats on a normal diet (57 +/- 3%, young, vs. 61 +/- 2%, old). With high K feeding there was a significant increase in the young, 69 +/- 4%, but not in the old rats, 62 +/- 2%. Na-K ATPase activity was markedly reduced in the renal medulla of old rats on a regular or high K diet. In addition, the response to acute K loading was compared in acutely nephrectomized rats. In the young rats on a regular diet plasma K increased from 3.72 +/- 0.09 to 5.28 +/- 0.16 mEq/liter while with K ingestion the increase was significantly less, 3.62 +/- 0.07 to 4.75 +/- 0.12 mEq/liter. In the old rats plasma K increased similarly on a regular or high K diet, 3.68 +/- 0.10 to 5.68 +/- 0.33 mEq/liter and 3.76 +/- 0.06 to 5.97 +/- 0.30 mEq/liter, respectively. Thus, old rats have impaired renal and extrarenal adaptation, but they have a normal response to an acute K challenge. A reduction in Na-K ATPase may account for the defect in renal adaptation in the aged rats.     

Impaired glucose homeostasis in adult rats from hyperglycemic mothers

The purpose of our study was to investigate whether nondiabetic gestational hyperglycemia during fetal life could have additional effects on glucose homeostasis and insulin secretion in the adult rat. Hyperglycemia without the main other metabolic disorders and vascular injuries associated with diabetes was produced in unrestrained pregnant rats by continuous glucose infusion during the last week of pregnancy. Control rats were infused with distilled water. Compared with controls, the newborns from hyperglycemic rats were hyperglycemic and hyperinsulinemic. When studied longitudinally up to 3 mo, they showed slightly but significantly increased basal plasma glucose levels and normal basal insulin concentrations compared with controls. Glucose tolerance and insulin secretion in response to a glucose load (0.5 mg/kg, i.v.) were altered: Plasma glucose values were more increased at 5 min and remained higher 90 min after glucose injection; incremental plasma insulin values and the insulinogenic indexes (delta IRI/delta G) were always lower in rats from hyperglycemic mothers than in controls. These alterations were more and more marked with advancing age (1-3 mo). These data show that gestational hyperglycemia may lead to persistent impairment of glucose homeostasis and insulin secretion in the adult rat.