Background COVID-19 disease in kidney transplant (KT) recipients is associated with increased morbidity, mortality, and hospitalization rates. Unfortunately, KT recipients also have a reduced response to SARS-CoV-2 immunization. The primary aim of this study was to assess immunologic response to SARS-CoV-2 mRNA vaccines in pediatric kidney transplant recipients 12–18 years of age. Secondary aims were to assess response rates following a third immunization and determine factors that influence immunization response. Methods Pediatric KT recipients in a single tertiary center received SARS-CoV-2 mRNA vaccination as per local protocol. SARS-CoV-2 immunoglobulin (IgG) was measured following second and/or third vaccination. Demographics including patient factors (age, gender, and underlying disease), transplant factors (time and type of transplant), and immunosuppression (induction, maintenance, and immunomodulatory therapies such as IVIG) were collected from the medical records. Results Of 20 participants, 10 (50%) responded following a two-dose vaccine schedule, which increased to 15 (75%) after three doses. Maintenance immunosuppression affected immunologic response, with azathioprine demonstrating a higher rate of response to vaccine compared to mycophenolate (100% vs. 38%, p = 0.04). Increasing prednisolone dose had a negative impact on immunologic response (0.01 mg/kg/day increase: OR 1.60 95% CI 1.01 to 2.57). Tacrolimus dose and trough levels, age, time post-transplant, underlying disease, and other immunosuppression did not impact immunologic response. Conclusions Pediatric KT recipients had similar response rates following SARS-CoV-2 immunization as adult KT recipients. Immunologic response improved following a third immunization. Choice of antimetabolite and prednisolone dosing influenced the rate of response. Graphical abstract A higher resolution version of the Graphical abstract is available as Supplementary Information Supplementary Information The online version contains supplementary material available at 10.1007/s00467-022-05679-y.

Case progressOn further history, it was discovered that the family had been using alkaline water as an alternate source of oral fluids given its reported health benefits.Alkaline water is advertised as negatively charged water with a pH of 8-10. These properties are marketed to provide significant health benefits including increased energy levels, reduced effects of ageing and stress and reduced incidence of illness and disease. Alkaline water contains calcium and magnesium carbonate, both exogenous sources of absorbable alkaline.The consumption of alkaline water in this case resulted in a milk-alkali syndrome with hypercalcaemia, metabolic alkalosis and an acute on chronic kidney injury. It was not detected for several months, and as a result, had a significant negative impact on this patient and his family. He required frequent venepuncture, increased clinical reviews (further complicated by the current COVID-19 pandemic) and regular titration of medications. Fortunately, on cessation of the alkaline water, his creatinine returned to baseline and calcium and acid-base normalised.

Kidney tubules are responsible for the preservation of fluid, electrolyte and acid-base homeostasis via passive and active mechanisms. These physiological processes can be disrupted by inherited or acquired aetiologies. The net result is a tubulopathy. It is important to make a prompt and accurate diagnosis of tubulopathies in children and young adults. This allows timely and appropriate management, including disease-specific therapies, and avoids complications such as growth failure. Tubulopathies can present with a variety of non-specific clinical features which can be diagnostically challenging. In this review, we build from this common anatomical and physiological understanding to present a tangible appreciation of tubulopathies as they are likely to be clinically encountered among affected children and young adults.

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