Renal Tubular Acidosis Type I with Prominent Hypokalemia and Nephrolithiasis as a Presentation of Sjögren's/Systemic Lupus Erythematosus Disease

Case report: disease mechanisms and medical management of calcium nephrolithiasis in rheumatologic diseases

Background

Nephrolithiasis as a feature of rheumatologic diseases is under recognized. Understanding presenting features, diagnostic testing is crucial to proper management.

Case presentation

A 32 year old woman with a history of recurrent complicated nephrolithiasis presented to a rheumatologist for a several month history of fatigue, dry eyes, dry mouth, arthralgias. She had a positive double-stranded DNA, positive SSA and SSB antibodies. She was diagnosed with Systemic Lupus erythematosus (SLE) and Sjogren's syndrome and was started on mycophenalate mofetil. Of relevance was a visit to her local emergency room 4 years earlier with profound weakness with unexplained marked hypokalemia and a non-anion gap metabolic acidosis. Approximately one year after that episode she developed flank pain and nephrocalcinosis. She had multiple issues over the ensuing years with stones and infections on both sides. Interventions included extracorporeal shockwave lithotripsy as well as open lithotomy and eventual auto-transplantation of left kidney for recurrent ureteric stenosis. 24 h stone profile revealed marked hypocitraturia, normal urine calcium, normal urine oxalate and uric acid. She was treated with potassium citrate. Mycophenolate was eventually stopped due to recurrent urinary tract infections and she was started on Belimumab. Because of recurrent SLE flares, treatment was changed to Rituximab (every 6 months) with clinical and serologic improvement. Her kidney stone frequency gradually improved and no further interventions needed although she continued to require citrate repletion for hypocitraturia.

Conclusions

Nephrolithiasis can be a prominent and even presenting feature in Sjogrens syndrome as well as other rheumatologic diseases. Prompt recognition and understanding disease mechanisms is important for best therapeutic interventions for kidney stone prevention as well as treatment of underlying bone mineral disease.

Kidney Stone Prevention

Kidney stone disease (KSD) (alternatively nephrolithiasis or urolithiasis) is a global health care problem that affects almost people in developed and developing countries. Its prevalence has been continuously increasing with a high recurrence rate after stone removal. Although effective therapeutic modalities are available, preventive strategies for both new and recurrent stones are required to reduce physical and financial burdens of KSD. To prevent kidney stone formation, its etiology and risk factors should be first considered. Low urine output and dehydration are the common risks of all stone types, whereas hypercalciuria, hyperoxaluria, and hypocitraturia are the major risks of calcium stones. In this article, up-to-date knowledge on strategies (nutrition-based mainly) to prevent KSD is provided. Important roles of fluid intake (2.5-3.0 L/d), diuresis (>2.0-2.5 L/d), lifestyle and habit modifications (for example, maintain normal body mass index, fluid compensation for working in high-temperature environment, and avoid cigarette smoking), and dietary management [for example, sufficient calcium at 1000-1200 mg/d, limit sodium at 2 or 3-5 g/d of sodium chloride (NaCl), limit oxalate-rich foods, avoid vitamin C and vitamin D supplements, limit animal proteins to 0.8-1.0 g/kg body weight/d but increase plant proteins in patients with calcium and uric acid stone and those with hyperuricosuria, increase proportion of citrus fruits, and consider lime powder supplementation] are summarized. Moreover, uses of natural bioactive products (for example, caffeine, epigallocatechin gallate, and diosmin), medications (for example, thiazides, alkaline citrate, other alkalinizing agents, and allopurinol), bacterial eradication, and probiotics are also discussed. Adv Nutr 2023;x:xx-xx.

Distal Renal Tubular Acidosis in Patients with Autoimmune Diseases—An Update on Pathogenesis, Clinical Presentation and Therapeutic Strategies

Distal renal tubular acidosis (DRTA) has been reported in association with autoimmune diseases, such as Sjögren’s syndrome, systemic lupus erythematosus (SLE), autoimmune hepatitis, primary biliary cirrhosis, rheumatoid arthritis and autoimmune thyroiditis. Whether we talk about the complete or incomplete form of DRTA associated with autoimmune diseases, the real incidence is unknown because asymptomatic patients usually are not identified, and most of the reported cases are diagnosed due to severe symptoms secondary to hypokalemia, a frequent finding in these cases. The mechanisms involved in DRTA in patients with autoimmune diseases are far from being fully elucidated and most of the data has come from patients with Sjögren’s syndrome. This review will present different hypotheses raised to explain this association. Also, aiming for a better understanding of the association between autoimmune diseases and DRTA, our review summarizes data from 37 case reports published in the last five years. We will emphasize data regarding clinical presentation, biological alterations, treatment and outcome. A very important question is whether immunosuppressive therapy is helpful in DRTA associated with autoimmune diseases. Because the pathology is rather rare, treatment is not standardized, and reported results are often contradictory. Corticosteroids are frequently used, but multiple other immunosuppressive drugs have been proposed and will be approached in this review.