Symptomatic renal tubular acidosis (RTA) in patients with systemic lupus erythematosus: an analysis of six cases with new association of type 4 RTA

Variables Associated With Hyperkalemic Renal Tubular Acidosis in Solid Organ Transplant Recipients

INTRODUCTION

The occurrence of hyperkalemic renal tubular acidosis (RTA) in the post-transplantation period is likely underestimated, and its identification remains important to offer adequate medical management. Transplant recipients frequently present with clinical and biological characteristics that may be associated with the occurrence of this complication.

METHODS

This was a single-center retrospective study that compared transplanted patients with hyperkalemic RTA and a control group to identify variables associated with the occurrence of this complication. Fisher's exact test and the Mann-Whitney test, followed by multivariate logistic regression, were applied to test whether there was a significant association between hyperkalemic RTA and different variables.

RESULTS

Kidney and heart transplant recipients were at greater risk of developing RTA than lung transplant recipients (p = 0.016). There was also a significant association between the development of RTA and kalemia (p < 0.01), chloremia (p < 0.01), and bicarbonatemia (p < 0.01). The significant impact of these last three variables was confirmed by the results of the multivariate logistic regression. Residual serum tacrolimus levels (p = 0.13) and creatinine levels (p = 0.17) of renal transplant patients were not significantly associated with hyperkalemic RTA.

CONCLUSION

The type of transplanted organ, kalemia, chloremia, and bicarbonatemia were significantly associated with the occurrence of hyperkalemic RTA. This study calls into question certain approaches to managing this complication proposed in a number of case reports, such as reducing the target serum residual of tacrolimus or discontinuing trimethoprim-sulfamethoxazole (TMP-SMX) in favor of another antibiotic prophylactic agent, potentially exposing patients to graft rejection and opportunistic infections.

Systemic lupus erythematosus complicated with Fanconi syndrome: a case report and literature review

Background

Systemic lupus erythematosus is an autoimmune disease with diverse clinical manifestations. The symptoms of SLE in children are more atypical than adults. Childhood SLE complicated with Fanconi syndrome is extremely rare and even more difficult to diagnose.

Case presentation

This article reports a preschool boy with SLE who presented with renal tubular acidosis, accompanied by weakness in both lower limbs, delayed growth, and malnutrition. It was later found that the patient had the complication of Fanconi syndrome with renal tubular acidosis. Ultimately, renal biopsy confirmed lupus nephritis. The patient was treated with corticosteroid combined with mycophenolate mofetil, hydroxychloroquine, and belimumab. The symptoms of the child were relieved.

Conclusion

Here we report an extremely rare case of childhood SLE complicated with Fanconi syndrome. There has been no similar clinical report. It is necessary to be alert to the possibility of atypical SLE in children to avoid missed diagnosis and misdiagnosis.

Ibuprofen-Induced Renal Tubular Acidosis: Case Report on a Not-So-Basic Clinical Conundrum

Rationale

Renal tubular acidosis (RTA) is a cause of non-anion gap metabolic acidosis (NAGMA) that is infrequently diagnosed and is due to various underlying etiologies that impair the kidney's ability to retain bicarbonate or excrete acid. Ibuprofen is an over-the-counter non-steroidal anti-inflammatory medication that is used by patients widely for a variety of reasons. Although it is well known that ibuprofen and other non-steroidal anti-inflammatory drugs may have nephrotoxic effects, the role of ibuprofen as a cause of RTA and hypokalemia is not well recognized.

Presenting Concerns

A 66-year-old man with chemotherapy-treated lymphoma in remission and ongoing heavy ibuprofen use for chronic pain presented to hospital with a 1-week history of increasing lethargy and otherwise unremarkable review of systems. Investigations showed acute kidney injury, hypokalemia, hyperchloremia, and NAGMA with elevated urinary pH and positive urine anion gap.

Diagnoses

The final diagnosis of distal RTA secondary to ibuprofen was made after ruling out gastrointestinal bicarbonate loss and additional secondary causes of RTA, including other medications, autoimmune conditions, and obstructive uropathy.

Interventions

The patient was admitted and treated with intravenous sodium bicarbonate for 24 hours with correction of hypokalemia via oral supplementation. His ibuprofen-containing medication was discontinued.

Outcomes

His acute kidney injury and electrolyte abnormalities resolved within 48 hours of initiating treatment with concurrent resolution of his lethargy. He was discharged home and advised to stop taking ibuprofen.

Lessons Learned

We report a case of patient with hypokalemia and NAGMA secondary to ibuprofen and highlight the importance of monitoring for this side effect in patients taking ibuprofen.

Kidney Stones, Proteinuria and Renal Tubular Metabolic Acidosis: What Is the Link?

Kidney stone disease represents a rare cause of chronic kidney disease (2−3%) but has severe clinical consequences. Type 1 renal tubular acidosis is a strong lithogenic condition mainly related to primary Sjögren syndrome. This study aimed to illustrate an unusual presentation of Sjögren syndrome to improve the knowledge about rare kidney stone diseases, and to provide clues for the diagnostic approach in this specific condition. We report the case of a 35-year-old Indian woman with severe nephrocalcinosis and chronic kidney disease with tubular proteinuria who presented for metabolic assessment. We found advanced chronic kidney disease, low serum bicarbonate, permanent alkaline urine with pH at ~7.1, and severe hypocitraturia corresponding to type 1 renal tubular acidosis. The erythrocyte sedimentation rate was high. Serological screening for HAV, HBV, HCV, HIV, EBV was negative and complement was normal. Autoimmune screening showed antinuclear antibodies (>1/1.280) with anti-SSA, anti-SSA/Ro52 and anti-SSB antibodies. Genetic testing excluded an inherited cause of renal tubular acidosis. A renal biopsy showed moderate chronic tubulo-interstitial nephritis without any glomerular involvement. Primary Sjögren syndrome with significant renal involvement was considered, and corticosteroids were then subsequently initiated in combination with potassium citrate with vitamin D substitution. Only partial improvement was observed in electrolytes disturbance. After 15 months, her renal function remained stable. In conclusion, nephrocalcinosis could be the first manifestation of severely impacting diseases such as primary Sjögren syndrome. Chronic kidney disease, bilateral nephrocalcinosis, and metabolic acidosis can be linked through type 1 renal tubular acidosis. Therefore, autoimmune screening for Sjögren syndrome should be considered in such cases.

Idiopathic Hypokalemia in Lupus Nephritis: A Newly Recognized Entity

Background

Various causes of hypokalemia (HK) from renal potassium wasting, including distal renal tubular acidosis (RTA), have been described in lupus nephritis (LN). We report a phenomenon of otherwise unexplained HK among a population with LN.

Methods

From our population of 403 patients with LN, we identified a cohort of 20 patients with idiopathic HK, defined by serum potassium <3.5 mmol/L without any apparent explanation. This cohort is compared with 90 LN controls (CON) and ten patients with LN with distal RTA from the same population.

Results

The patients with HK had lower median serum potassium compared with CON and RTA subjects (3.26 versus 4.00 versus 3.75 mmol/L, respectively; P<0.001). The median serum bicarbonate was normal in HK and CON, but low in RTA (26.0 versus 25.0 versus 19.4 mmol/L; P<0.001). The median urine pH was abnormally high only in the RTA group (6.00 versus 6.25 versus 6.67; P=0.012). The median serum magnesium was modestly lower in HK compared with the CON and RTA groups (1.73 versus 2.00 versus 1.85 mg/dl; P=0.002). Although both HK and RTA showed a higher rate of seropositivity than CON for anti-Ro/SSA (79% and 80% versus 37%, respectively; P<0.001), only HK revealed a higher rate of seropositivity than CON for anti-RNP (84% versus 42%; P=0.003) and only RTA showed a higher rate of seropositivity than CON for anti-La/SSB (40% versus 12%; P=0.05).

Conclusions

A syndrome of idiopathic HK was revealed in 20 out of 403 (5%) of patients within our LN population, and proved to be distinct from the RTA that occurs in LN. Furthermore, it was associated with a distinct pattern of autoantibodies. We speculate that idiopathic HK is the result of a novel target of autoimmunity in LN, affecting renal tubular potassium transport.

Renal Tubular Acidosis in Patients with Systemic Lupus Erythematosus

OBJECTIVE

Renal tubular acidosis (RTA) is a clinical manifestation that occurs with insufficiency in restoring bicarbonate or disruption in hydrogen ion elimination as a result of a disruption in tubulus functions, causing normal anion gap-opening metabolic acidosis. In the present study, we aimed to investigate the prevalence of RTA in the largest systemic lupus erythematosus (SLE) patient population to date.

MATERIALS AND METHODS

SLE patients, who were followed up in 2 different healthcare centers, were included. Patients with metabolic acidosis (pH <7.35 and HCO3 <22 mEq/L) in venous blood gas analysis were determined. The serum and urine anion GAP of these patients were estimated, and the urine pH was assessed. RTA presence was evaluated as metabolic acidosis with a normal serum anion gap and a positive urine anion GAP.

RESULTS

A total of 108 patients were included in the present study. The mean age of the patients was 41.5 ± 1.2 and 87% were female. The SLE diagnosis duration was 75 ± 5 months. The mean creatinine value ​​was 0.6 ± 0.1 mg/dL and the mean eGFR was 111 ± 2 mL/min. According to the blood gas analysis, 18 patients (16.7% of the total) had RTA. Sixteen of these patients had type 1 RTA and 2 had type 2 RTA; type 4 RTA was not determined in any of the patients.

CONCLUSION

RTA should be considered in SLE patients even if they have normal eGFR values. This is the largest study to examine the prevalence of RTA in SLE patients in the literature.

Value of monitoring urine ammonia at time of biopsy in patients with lupus nephritis

Objective

Although lupus nephritis (LN) is mostly characterized by glomerular involvement, tubular injury is indispensable in its pathogenesis and progression. The purpose of this study is to examine associations between urinary acidification function and clinical and pathological features in LN.

Methods

A total of 103 patients with renal biopsy-proven LN were included, and clinical parameters and laboratory data were obtained from the medical records. Plasma samples, 24-h urine samples and the urinary acidification function, including urine pH, titratable acid, and ammonia, were collected within 3 days before the day of renal biopsy. The correlations between defects of acid excretion and clinical and pathological features were then assessed. Logistic regression analysis was used to assess factors associated with the presence of nephrotic range proteinuria.

Results

The urine ammonia level was inversely correlated with SLEDAI-2 K scores, rSLEDAI scores, serum creatinine levels and proteinuria, while it was positively correlated with eGFR. And urine titratable acid was only inversely correlated with rSLEDAI scores and proteinuria. Moreover, urine ammonia had significant negative correlations with AI scores, interstitial inflammatory cell infiltration, CI scores, glomerular sclerosis, fibrous crescents, tubular atrophy and interstitial fibrosis. And urine titratable acid was mainly inversely correlated with CI scores. Furthermore, univariate logistic analyses identified that both urine titratable acid and ammonia were correlated with the presence of nephrotic range proteinuria. After the adjustment for chronicity index and eGFR in a multivariate logistic analysis, only urine titratable acid was still identified as an independent risk factor for the occurrence of nephrotic range proteinuria.

Conclusions

Urine ammonia was associated with clinical and pathological features of chronicity and tubulointerstitial disease activity among patients with lupus nephritis. Furthermore, the strong association between urinary protein and titratable acid excretion at the time of kidney biopsy is significant even after adjusting for the chronicity index and eGFR at biopsy.

iTRAQ-Based Comparative Proteomics Analysis of Urolithiasis Rats Induced by Ethylene Glycol

Nephrolithiasis is a frequent chronic urological condition with a high prevalence and recurrence rate. Proteomics studies on urolithiasis rat models are highly important in characterizing the pathophysiology of kidney stones and identifying potential approaches for preventing and treating kidney stones. The isobaric tags for relative and absolute quantification (iTRAQ) were performed to identify differentially expressed proteins (DEPs) in the kidney between urolithiasis rats and control rats. The results showed that 127 DEPs (85 upregulated and 42 downregulated) were identified in urolithiasis and control rats. The functions of DEPs were predicted by Gene Ontology (GO) analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis, and protein-protein interaction (PPI) network analysis. The expression of four upregulated proteins (Tagln, Akr1c9, Spp1, and Fbn1) and four downregulated proteins (Hbb, Epb42, Hmgcs2, and Ca1) were validated by parallel reaction monitoring (PRM). Proteomics studies of ethylene glycol-induced urolithiasis rat models using iTRAQ and PRM helped to elucidate the molecular mechanism governing nephrolithiasis and to identify candidate proteins for the treatment of kidney stones.

Systematic review and case report: Systemic lupus erythematosus with renal tubular acidosis

Immune profile assessment-particularly for SLE-and subsequent specific therapy are beneficial in patients with persisting unexplained hyperkalemic or hypokalemic paralysis, especially in case of isolated RTA.

Systemic lupus erythematosus complicated by a Gitelman-like syndrome in an 8-year-old girl

An 8-year-old girl with recently diagnosed Systemic Lupus Erythematosus (SLE) (class 4 lupus nephritis with autoimmune hemolytic anemia) presented to the pediatric nephrology clinic with polyuria, tiredness and cramps; laboratory investigations revealed refractory hypokalemia, hypomagnesemia, metabolic alkalosis, hypocalciuria and hyperchloriuria. There was no history of diuretic administration. These features were consistent with the Gitelman syndrome. She required large doses of potassium and magnesium supplementation along with spironolactone, for normalization of the serum potassium and magnesium levels. Immunosuppressive therapy was continued with cyclophosphamide pulses administered on a monthly basis. The doses of potassium and magnesium supplements were tapered off over the next 6 months. The clinical exome sequencing was negative for any mutations in the SLC12A3 gene. An 'acquired' form of Gitelman syndrome has been reported earlier in association with Sjogren syndrome and systemic sclerosis. Though tubular disorders such as renal tubular acidosis have been reported in association with SLE, a Gitelman-like syndrome has not been reported earlier. This case adds Gitelman-like tubulopathy to the clinical spectrum of tubular disorders complicating SLE.

Presence of serum autoantibodies to vacuolar H+ -ATPase in patients with renal tubular acidosis

OBJECTIVE

Concomitant presence of renal tubular acidosis (RTA) and autoimmune diseases is indicative of the potential role of immune factors in the pathogenesis of RTA. Our study aimed to detect the serum antibodies to renal tubular epithelial cells in RTA patients.

METHODS

We enrolled 11 RTA patients, eight primary Sjögren's syndrome (pSS) patients and eight healthy controls (HC). Serum biochemical test, urinary regular test, and 24 hours urinary protein quantification were measured using a fully automated analyzer. Immunofluorescence assay was performed to detect the antibodies to subunit B1 and subunit B2 of v-H+-ATPases (adenosine triphosphatases) in the serum of the participants.

RESULTS

Clinically, RTA patients showed hyperchloremia, acidosis and paradoxical alkaline urine. We detected the serum antibodies to renal tubular epithelial cells and there were 6/11 positive in RTA patients, much higher than that in the pSS group (0/8) and the HC group (0/8). Subsequently, we demonstrated that in normal renal tissue, the B1 subunit of v-H+-ATPase specifically expressed in intercalated cells, while the B2 subunit continuously expressed along the lumen of renal tubular epithelial cells. Moreover, the antibody to subunit B1/B2 of v-H+-ATPase was positive in the sera of 6 RTA patients (54%), while it was negative in both the pSS and HC group.

CONCLUSIONS

We detected the presence of serum autoantibodies to subunit B1 and subunit B2 of v-H⁺ -ATPase in RTA patients. Our findings may provide novel mechanism insights into the pathogenesis of RTA and the potential diagnostic utility of antibodies to v-H⁺ -ATPase in the classification of RTA.

Hypokalemic Paralysis: A Hidden Card of Several Autoimmune Diseases

Acute hypokalemic paralysis is a rare and potentially fatal condition, with few related causes, one of which highlights distal renal tubular acidosis (dRTA). Distal renal tubular acidosis is a rare complication of several autoimmune diseases such as systemic lupus erythematosus, Sjögren's syndrome, and Hashimoto thyroiditis. We report a case of a lupic patient who presented rapidly progressive quadriparesis in the context of active renal disease. Research revealed severe refractory hypokalemia, metabolic acidosis, and alkaline urine suggestive of dRTA. We diagnosed Sjögren's syndrome based on sicca symptoms, an abnormal salivary glands' nuclear scan and the presence of anti-Ro/SSA and anti-La/SSB. In addition, the finding of thyroid peroxidase, thyroglobulin antibodies, and hypothyroidism led us to the diagnosis of Hashimoto thyroiditis. Due to the active renal involvement on the context of systemic lupus erythematosus and Sjögren's syndrome, the patient received immunosuppression with rituximab, resulting in a progressive and complete improvement.

Distal Renal Tubular Acidosis Associated with Celiac Disease and Thyroiditis

BACKGROUND

Association of distal renal tubular acidosis (RTA) with autoimmune diseases is extremely rare in children.

CASE CHARACTERISTICS

12-year-old girl with distal RTA. Despite resolution of acidosis on bicarbonate, she continued to have poor growth and delayed puberty. Investigations revealed autoimmune thyroiditis and celiac disease.

OUTCOME

Levothyroxine and gluten-free diet were initiated. Child gained height and weight and had onset of puberty after gluten withdrawal.

MESSAGE

Distal RTA in children may rarely be of autoimmune etiology.

Primary sclerosing cholangitis: a new cause of distal renal tubular acidosis

We describe the first case of distal renal tubular acidosis (dRTA) associated with primary sclerosing cholangitis. A 26-year-old Lao-Thai male patient presented with severe jaundice, metabolic acidosis and hypokalaemia. He was diagnosed of dRTA. Liver transplantation resulted in correction of electrolyte disturbances and hyperbilirubinaemia. A fludrocortisone-furosemide test revealed normal urinary acidification, demonstrating no residual dRTA. This observation suggests that dRTA may be an early manifestation of bilirubin-associated nephropathy or the consequence of an immune mechanism.

Renal tubular acidosis type IV as a complication of lupus nephritis

Renal tubular acidosis (RTA) is a rare complication of renal involvement of systemic lupus erythematosus (SLE). We describe a 24-year-old male with type IV lupus nephropathy as a presenting manifestation of SLE. He presented with improvement of renal function following induction therapy with three pulses of methylprednisolone and 500 mg biweekly pulses of cyclophosphamide. However, a week after the first pulse of cyclophosphamide, the patient presented with a significant increase in legs edema and severe hyperkalemia. Type IV RTA associated with hyporeninemic hypoaldosteronism was suspected in the presence of metabolic acidosis with a normal anion gap, severe hyperkalemia without worsening renal function, and urinary pH of 5. RTA was confirmed with a transtubular potassium concentration gradient of 2 and low levels of plasma aldosterone, renin, angiotensin II, and cortisol. Intravenous bicarbonate, high-dose furosemide, and fludrocortisone were administered with normalization of potassium levels and renal function.

Acute-onset paralysis in a patient of rheumatoid arthritis

Renal tubular acidosis (RTA) is a disorder of renal acidification characterized by inability to acidify urine to pH < 5.5 despite the presence of severe systemic metabolic acidosis and hypokalemia. Hypokalemia leads to acute-onset paralysis and may be a presenting manifestation of RTA. Its association with various autoimmune disease has been reported previously in published reports, but has not been much emphasized. We, hereby, report a case of RTA that presented during the flare of rheumatoid arthritis (RA). A 42-year-old female, a known case of RA for 5 years, presented with persistent joint pain for 1 week and acute-onset quadriparesis for 3 days. Primary investigations revealed hypokalemia with metabolic acidosis. She was managed conservatively with potassium supplements and bicarbonate supplements along with steroids and disease-modifying anti-rheumatic drugs. Such a presentation of renal tubular acidosis in a patient during the flare of rheumatoid arthritis is distinctly rare and previously unreported in published studies.

Renal tubular dysfunction presenting as recurrent hypokalemic periodic quadriparesis in systemic lupus erythematosus

We report recurrent hypokalemic periodic quadriparesis in a 30-year-old woman. Patient had also symptoms of multiple large and small joint pain, recurrent oral ulceration, photosensitivity and hair loss that were persisting since last 6 months and investigations revealed systemic lupus erythematosus (SLE) with distal tubular acidosis. Our patient was successfully treated with oral potassium chloride, sodium bicarbonate, hydroxychloroquine and a short course of steroids. Thus, tubular dysfunction should be carefully assessed in patients with SLE.

Distal renal tubular acidosis associated with Sjogren syndrome

Renal tubular acidosis is a common cause of normal anion gap metabolic acidosis but these disorders can be easily missed or misdiagnosed. We highlight the approach to assessing renal tubular acidosis by discussing a case study with a temporal data set collected over more than 5 weeks. We highlight the principles and the necessary information required for a diagnosis of classic distal renal tubular acidosis. We also briefly review several aspects of type 1 renal tubular acidosis related to autoimmune disease, drugs and thyroid disorders.

Everything you need to know about distal renal tubular acidosis in autoimmune disease

Renal acid–base homeostasis is a complex process, effectuated by bicarbonate reabsorption and acid secretion. Impairment of urinary acidification is called renal tubular acidosis (RTA). Distal renal tubular acidosis (dRTA) is the most common form of the RTA syndromes. Multiple pathophysiologic mechanisms, each associated with various etiologies, can lead to dRTA. The most important consequence of dRTA is (recurrent) nephrolithiasis. The diagnosis is based on a urinary acidification test. Potassium citrate is the treatment of choice.

Renal involvement in autoimmune connective tissue diseases

Connective tissue diseases (CTDs) are a heterogeneous group of disorders that share certain clinical presentations and a disturbed immunoregulation, leading to autoantibody production. Subclinical or overt renal manifestations are frequently observed and complicate the clinical course of CTDs. Alterations of kidney function in Sjögren syndrome, systemic scleroderma (SSc), auto-immune myopathies (dermatomyositis and polymyositis), systemic lupus erythematosus (SLE), antiphospholipid syndrome nephropathy (APSN) as well as rheumatoid arthritis (RA) are frequently present and physicians should be aware of that.In SLE, renal prognosis significantly improved based on specific classification and treatment strategies adjusted to kidney biopsy findings. Patients with scleroderma renal crisis (SRC), which is usually characterized by severe hypertension, progressive decline of renal function and thrombotic microangiopathy, show a significant benefit of early angiotensin-converting-enzyme (ACE) inhibitor use in particular and strict blood pressure control in general. Treatment of the underlying autoimmune disorder or discontinuation of specific therapeutic agents improves kidney function in most patients with Sjögren syndrome, auto-immune myopathies, APSN and RA.In this review we focus on impairment of renal function in relation to underlying disease or adverse drug effects and implications on treatment decisions.

Cytomegalovirus infection causes morbidity and mortality in patients with autoimmune diseases, particularly systemic lupus: in a Chinese population in Taiwan

To investigate the clinical outcome of cytomegalovirus (CMV) infection in febrile hospitalized patients with autoimmune diseases, mostly systemic lupus erythematosus (SLE). Fifty-four febrile patients were analyzed retrospectively. Half were diagnosed as CMV infection, by positive CMV pp65 antigenemia assay. Clinical and laboratory data between two groups were compared. Correlation between laboratory data and SELENA-SLEDAI scores/mortality were analyzed in the CMV infection group. Receiver operating characteristic analysis was performed to determine the cutoff points of different parameters for predicting mortality or morbidity. The CMV infection group received a higher corticosteroid dosage (mean 26.3 mg/day) and a higher percentage of azathioprine use before admission than the non-CMV infection group. In the former, the deceased subgroup had a significantly higher number of infected leukocytes for CMV (shortened as CMV counts, P = 0.013), more cases of bacterial infection (P = 0.090), and a higher SLE disease activity index score (P = 0.072) than the alive subgroup. The CMV infection group had lower lymphocyte count and more positive bacterial infection than the non-CMV infection group did (P = 0.013 and P = 0.027, respectively). A level of 25 CMV particles/5 × 10(5) polymorphonuclear neutrophils (PMN) was the best cutoff point for predicting CMV-associated mortality, with a sensitivity of 75.0% and specificity of 72.2%. Moderate dose (30 mg/day) of prednisolone or azathioprine use predisposes patients with autoimmune diseases to CMV infection with concurrent bacterial infection. In particular, peak CMV counts at 25/5 × 10(5) PMN or low lymphocyte counts predict mortality or morbidity, respectively.

Systemic lupus erythematosus associated with type 4 renal tubular acidosis: a case report and review of the literature

Introduction

Type 4 renal tubular acidosis is an uncommon clinical manifestation of systemic lupus erythematosus and has been reported to portend a poor prognosis. To the best of our knowledge, this is the first case report which highlights the successful management of a patient with systemic lupus erythematosus complicated by type 4 renal tubular acidosis who did not do poorly.

Case presentation

A 44-year-old Hispanic woman developed a non-anion gap hyperkalemic metabolic acidosis consistent with type 4 renal tubular acidosis while being treated in the hospital for recently diagnosed systemic lupus erythematosus with multi-organ involvement. She responded well to treatment with corticosteroids, hydroxychloroquine and mycophenolate mofetil. Normal renal function was achieved prior to discharge and remained normal at the patient's one-month follow-up examination.

Conclusion

This case increases awareness of an uncommon association between systemic lupus erythematosus and type 4 renal tubular acidosis and suggests a positive impact of early diagnosis and appropriate immunosuppressive treatment on the patient's outcome.