A Bartter's-like syndrome from capreomycin, and a similar gentamicin tubulopathy

Metabolic alkalosis in cystic fibrosis: from vascular volume depletion to impaired bicarbonate excretion

Cystic fibrosis (CF) is the most common life-threatening genetic disease in the United States and among people of European descent. Despite the widespread distribution of the cystic fibrosis transmembrane conductance regulator (CFTR) along kidney tubules, specific renal phenotypes attributable to CF have not been well documented. Recent studies have demonstrated the downregulation of the apical Cl-/HCO3 - exchanger pendrin (Slc26a4) in kidney B-intercalated cells of CF mouse models. These studies have shown that kidneys of both mice and humans with CF have an impaired ability to excrete excess HCO3 -, thus developing metabolic alkalosis when subjected to excess HCO3 - intake. The purpose of this minireview is to discuss the latest advances on the role of pendrin as a molecule with dual critical roles in acid base regulation and systemic vascular volume homeostasis, specifically in CF. Given the immense prevalence of vascular volume depletion, which is primarily precipitated via enhanced chloride loss through perspiration, we suggest that the dominant presentation of metabolic alkalosis in CF is due to the impaired function of pendrin, which plays a critical role in systemic vascular volume and acid base homeostasis.

Metabolic Rewiring of Mycobacterium tuberculosis upon Drug Treatment and Antibiotics Resistance

Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), remains a significant global health challenge, further compounded by the issue of antimicrobial resistance (AMR). AMR is a result of several system-level molecular rearrangements enabling bacteria to evolve with better survival capacities: metabolic rewiring is one of them. In this review, we present a detailed analysis of the metabolic rewiring of Mtb in response to anti-TB drugs and elucidate the dynamic mechanisms of bacterial metabolism contributing to drug efficacy and resistance. We have discussed the current state of AMR, its role in the prevalence of the disease, and the limitations of current anti-TB drug regimens. Further, the concept of metabolic rewiring is defined, underscoring its relevance in understanding drug resistance and the biotransformation of drugs by Mtb. The review proceeds to discuss the metabolic adaptations of Mtb to drug treatment, and the pleiotropic effects of anti-TB drugs on Mtb metabolism. Next, the association between metabolic changes and antimycobacterial resistance, including intrinsic and acquired drug resistance, is discussed. The review concludes by summarizing the challenges of anti-TB treatment from a metabolic viewpoint, justifying the need for this discussion in the context of novel drug discovery, repositioning, and repurposing to control AMR in TB.

An unusual complication secondary to kanamycin use in a patient of multidrug-resistant pulmonary tuberculosis

Gitelman syndrome (GS) is a rare genetic renal disease characterized by hypomagnesemia, hypokalemia, hypocalciuria, and metabolic alkalosis. It usually presents in late childhood or early adulthood. A 30-year-old female diagnosed case of multidrug-resistant (MDR-TB) pulmonary tuberculosis 2 months ago presented to our outpatient department with intermittent painful spasms in all four limb muscles. Her treatment regimen consisted of kanamycin, levofloxacin, cycloserine, and ethionamide. On further evaluation, her investigations revealed hypokalemia, hypocalcemia, hypomagnesemia, metabolic alkalosis with normal serum creatinine level. She was initially treated with intravenous calcium and potassium. However, the electrolyte abnormalities and metabolic alkalosis persisted. All her lab parameters became normal after discontinuing kanamycin and electrolyte replacement for 4 weeks. She was discharged and advised to continue her antituberculosis treatment. There was no recurrence of symptoms on further follow up.

Acquired autoimmune Bartter syndrome in a patient with primary hypothyroidism

We describe an unusual clinical presentation of autoimmune Bartter syndrome in a patient with primary hypothyroidism. A 65-year-old female patient was admitted with neuromuscular weakness associated with hypokalemia and metabolic alkalosis. She had a suboptimal response to potassium supplementation and potassium-sparing diuretic resulting in re-hospitalization with the same symptoms. A detailed serum and urinary biochemistry analysis in the absence of other causes of potassium wasting helped diagnose Bartter syndrome, a rare entity in adults. An autoimmune profile showed anti-Scl-70 antibody to be positive, although she did not develop other systemic features of the disease. Our patient responded to a steroid-based regimen potassium supplement, Indomethacin, and aldosterone antagonist with remarkable resolution of symptoms and correction of electrolyte derangement. We reviewed the literature to search for similar cases and included twenty-seven full-length publications on acquired and autoimmune causes of Bartter syndrome. Our case highlights the fact that hypokalemia with metabolic alkalosis in an adult patient should prompt clinicians to evaluate for common and uncommon conditions. While assessing for abnormal conditions, acquired Bartter syndrome should be considered if a patient has an underlying autoimmune, endocrine, or connective tissue disease.

Electrolyte and Acid-Base Disorders Triggered by Aminoglycoside or Colistin Therapy: A Systematic Review

Aminoglycoside or colistin therapy may alter the renal tubular function without decreasing the glomerular filtration rate. This association has never been extensively investigated. We conducted a systematic review of the literature following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses recommendations. Databases searched included United States National Library of Medicine, Excerpta Medica, and Web of Science. For the final analysis, we evaluated 46 reports, published after 1960, describing 82 cases. A total of 286 electrolyte and acid-base disorders were reported. Hypomagnesemia, hypokalemia, and hypocalcemia were reported in more than three quarter of cases. Further disorders were, in decreasing order of frequency, metabolic alkalosis, hyponatremia, hypophosphatemia, hypouricemia, hypernatremia, and metabolic acidosis. Six electrolyte and acid-base disorders were reported in seven cases, five in 12 cases, four in 16 cases, three in 31 cases, two in 11 cases, and one in five cases. Laboratory features consistent with a loop of Henle/distal tubular dysfunction were noted in 56 (68%), with a proximal tubular dysfunction in three (3.7%), and with a mixed dysfunction in five (6.1%) cases. The laboratory abnormality was unclassified in the remaining 18 (22%) cases. Treatment with aminoglycosides or colistin may trigger a proximal tubular or, more frequently, a loop of Henle/distal tubular dysfunction.

Unusual Complication of Multidrug Resistant Tuberculosis

INTRODUCTION

Capreomycin is a second-line drug often used for multidrug-resistant tuberculosis which can result in nephrotoxic effects similar to other aminoglycosides. We describe a case of capreomycin induced Bartter-like syndrome with hypocalcemic tetany.

CASE REPORT

23-year-old female patient presented with carpopedal spasms and tingling sensations in hands. Patient was being treated with capreomycin for two months for tuberculosis. On further investigation, hypocalcemia, hyponatremia, hypomagnesemia, hypokalemia, and hypochloremic metabolic alkalosis were noted. Vitamin D and serum PTH levels were within normal limits. Hypercalciuria was confirmed by urine calcium/creatinine ratio. Calcium, potassium, and magnesium supplementation was given and capreomycin was discontinued. Electrolytes normalized in two days after cessation of capreomycin with no further abnormalities on repeat investigations.

DISCUSSION

Aminoglycosides can result in renal tubular dysfunction leading to Fanconi syndrome, Bartter syndrome, and distal tubular acidosis. Impaired mitochondrial function in the tubular cells has been hypothesized as the possible cause of these tubulopathies. Acquired Bartter-like syndrome phenotypically resembles autosomal dominant type 5 Bartter syndrome. Treatment consists of correction of electrolyte abnormalities, indomethacin, and potassium-sparing diuretics. Prompt diagnosis and treatment of severe dyselectrolytemia are warranted in patients on aminoglycoside therapy.

Drug-induced hypomagnesaemia : scope and management

Nearly 50 medications have been implicated as inducing hypomagnesaemia, sometimes based on insufficient data regarding clinical significance and frequency of occurrence. In fact, clinical effects attributed to hypomagnaesemia have been reported in only 17 of these drugs. A considerable amount of literature relating to individual drugs has been published, yet a comprehensive overview of this issue is not available and the hypomagnesaemic effect of a drug could be either overemphasised or under-rated. In addition, there are neither guidelines regarding treatment, prevention and monitoring of drug-induced hypomagnesaemia nor agreement as to what serum level of magnesium may actually be defined as 'hypomagnesaemia'. By compiling data from published papers, electronic databases, textbooks and product information leaflets, we attempted to assess the clinical significance of hypomagnesaemia induced by each drug. A practical approach for managing drug-induced hypomagnesaemia, incorporating both published literature and personal experience of the physician, is proposed. When drugs classified as inducing 'significant' hypomagnesaemia (cisplatin, amphotericin B, ciclosporin) are administered, routine magnesium monitoring is warranted, preventive treatment should be considered and treatment of hypomagnesaemia should be initiated with or without overt clinical manifestations. In drugs belonging to the 'potentially significant' category, among which are amikacin, gentamicin, laxatives, pentamidine, tobramycin, tacrolimus and carboplatin, magnesium monitoring is justified when either of the following occurs: clinical manifestations are apparent; persistent hypokalaemia, hypocalcaemia or alkalosis are present; other precipitating factors for hypomagnesaemia coexist; or treatment is with more than one potentially hypomagnesaemic drug. No preventive treatment is required and treatment should be initiated only if hypomagnesaemia is accompanied by symptoms or clinically significant relevant laboratory findings. In those drugs whose hypomagnesaemic effect is labelled as 'questionable', including furosemide and hydrochlorothiazide, routine monitoring and treatment are not required.

Hypokalemia among patients receiving treatment for multidrug-resistant tuberculosis

INTRODUCTION

Between January 1999 and December 2000, 125 patients in Lima, Peru were enrolled in individualized treatment for multidrug-resistant tuberculosis (MDR-TB). Hypokalemia was observed to be an important adverse effect encountered in this cohort.

OBJECTIVE

To identify risk factors associated with the development and persistence of hypokalemia during MDR-TB therapy, and to review the incidence and management of hypokalemia in patients receiving MDR-TB therapy.

METHODS

A retrospective case series of 125 patients who received individualized therapy for MDR-TB between January 1, 1999, and December 31, 2000.

RESULTS

Among 115 patients who were screened for electrolyte abnormalities, 31.3% had hypokalemia, defined as a potassium level of < 3.5 mEq/L. Mean serum potassium at time of diagnosis was 2.85 mEq/L. Diagnosis of low serum potassium occurred, on average, after 5.1 months of individualized therapy. Multivariate analysis of risk factors for this adverse reaction identified two causes: administration of capreomycin, and low initial body weight. Normalization of potassium levels was achieved in 86% of patients.

CONCLUSIONS

Electrolyte disturbance was frequently encountered in our cohort of patients with MDR-TB. Successful screening and management of hypokalemia was facilitated by training the health-care team in the use of a standardized algorithm. Morbidity from hypokalemia can be significant; however, effective management of this side effect is possible without sacrificing MDR-TB treatment efficacy.

Bartter syndrome complicated by immune complex nephropathy. Case report and literature review

The unusual coincidence of Bartter syndrome and C1q nephropathy is described and the literature reviewed. An African-American girl presented at 4 years of age with acute hyponatremic dehydration and failure to thrive. Persistent hypokalemic alkalosis and secondary hyperaldosteronism were found. The case was atypical for Bartter syndrome in that proteinuria (0.19 g/day) was present. Renal biopsy showed juxtaglomerular hyperplasia and C1q nephropathy. Molecular analysis showed deletion of the renal chloride channel gene (CLCNKB) typical of autosomal recessive childhood Bartter syndrome. Chronic sodium and potassium chloride replacement therapy together with indomethacin normalized her metabolic status, and she experienced catch-up growth. Proteinuria persisted, however. This is the first documentation of C1q nephropathy, in mild form, complicating autosomal recessive Bartter syndrome. This case shows the importance of the renal biopsy and of molecular analysis in delineating the cause of atypical nephropathy associated with Bartter syndrome. These findings add to the evidence of a possible association between the congenital syndrome and acquired immune complex nephropathy.

Effects of antibacterials on the unborn child: what is known and how should this influence prescribing

Antibacterials are among the most commonly prescribed drugs worldwide. In general, infections occur in pregnant women at much the same rate as in the general population. However, as a result of physiological changes brought about by pregnancy, some infections, such as those of the urinary tract, may have an increased incidence. It is important to remember that almost every drug crosses the placenta, ensuring that the unborn fetus is also exposed. When prescribing an antibacterial agent to a pregnant woman, it is important that the mother is treated appropriately while at the same time protecting the unborn child. Certain factors need to be addressed, such as the possible teratogenic risk, changes in pharmacokinetics and the potential toxicity of the drug. In this paper we have reviewed various classes of antibacterials which are commonly used during pregnancy, including penicillins, beta-lactam inhibitors, cephalosporins, macrolides, aminoglycosides, tetracyclines, lincosamides, fluoroquinolones, sulfonamides, nitrofurans, and anti-tubercular agents. Some of these drugs have been on the market for many years, whereas others are relatively new and increasingly popular, despite the fact that the older drugs remain very effective. After reviewing the evidence-based information from epidemiological studies, it appears that most antibacterial agents can be used relatively safely during pregnancy. Women who are pregnant should not be denied appropriate antibacterial therapy because of a lack of information. It is possible to treat the mother, while protecting the unborn child, by prescribing an agent that the causative bacteria is sensitive to, rather than a perceived 'safer' option that may not effectively treat the infection and which may also add to the growing problem of bacterial resistance.

Syndrome of hypokalemic metabolic alkalosis and hypomagnesemia associated with gentamicin therapy: case reports

Nephrotoxicity, as evidenced by renal insufficiency is a well-known consequence of gentamicin therapy. We report two patients with gentamicin-induced syndrome of hypokalemic metabolic alkalosis and hypomagnesemia. Both had complete recovery of renal tubular function after cessation of antibiotic therapy. These cases emphasize the need to routinely monitor patients receiving gentamicin therapy for electrolyte abnormalities to avoid potential morbidity.

Aminoglycosides inhibit hormone-stimulated Mg2+uptake in mouse distal convoluted tubule cells

The clinical use of aminoglycosides often leads to renal magnesium wasting and hypomagnesemia. Of the nephron segments, both the thick ascending limb of Henle's loop and the distal tubule play significant roles in renal magnesium conservation but the distal convoluted tubule exerts the final control of urinary excretion. An immortalized mouse distal convoluted tubule (MDCT) cell line has been extensively used to study the cellular mechanisms of magnesium transport in this nephron segment. Peptide hormones, such as parathyroid hormone (PTH), glucagon, calcitonin, and arginine vasopressin (AVP) stimulate Mg2+uptake in MDCT cells that is modulated by extracellular polyvalent cations, Ca2+and Mg2+. The present studies determined the effect of aminoglycosides on parathyroid hormone (PTH)-mediated cAMP formation and Mg2+uptake in MDCT cells. Gentamicin, a prototypic aminoglycoside, illicited transient increases in intracellular Ca2+from basal levels of 102 ± 13 nM to 713 ± 125 nM, suggesting a receptor-mediated response. In order to determine Mg2+transport, MDCT cells were Mg2+-depleted by culturing in Mg2+-free media for 16 h and Mg2+uptake was measured by microfluorescence after placing the depleted cells in 1.0 mM MgCl2. The mean rate of Mg2+uptake, d([Mg2+]i)/dt, was 138 ± 24 nM/s in control MDCT cells. Gentamicin (50 µM) did not affect basal Mg2+uptake (105 ± 29 nM/s), but inhibited PTH stimulated Mg2+entry, decreasing it from 257 ± 36 nM/s to 108 ± 42 nM/s. This was associated with diminished PTH-stimulated cAMP formation, from 80 ± 2.5 to 23 ± 1 pmol/mg protein·5 min. Other aminoglycosides such as tobramycin, streptomycin, and neomycin also inhibited PTH-stimulated Mg2+entry and cAMP formation. As these antibiotics are positively charged, the data suggest that aminoglycosides act through an extracellular polyvalent cation-sensing receptor present in distal convoluted tubule cells. We infer from these studies that aminoglycosides inhibit hormone-stimulated Mg2+absorption in the distal convoluted tubule that may contribute to the renal magnesium wasting frequently observed with the clinical use of these antibiotics.Key words: intracellular Mg2+, Mg2+uptake, aminoglycosides, gentamicin, tobramycin, streptomycin, neomycin, parathyroid hormone, microfluorescence, cAMP measurements.

Acute muscular paralysis in an adult with subclinical Bartter's syndrome associated with gentamicin administration

We report an adult case of asymptomatic Bartter's syndrome with the first presentation of hypokalemic paralysis triggered by gentamicin injection. Marked hypokalemia and hypomagnesemia associated with excessive kaliuresis and magnesiuria were found. Plasma renin activity and aldosterone concentration were high, but blood pressure was normal. Renal biopsy revealed hypercellularity of the renin-producing cell of the juxtaglomerular apparatus. Muscular paralysis subsided after potassium chloride supplementation. Hypokalemia was corrected with potassium and magnesium supplements and the use of diclofenac. To the best of our knowledge, there have been no reports of muscular paralysis associated with gentamicin in Bartter's syndrome.