Challenging case of hypernatraemia in infancy.

A 1-month-old male infant presented unwell with a fever and shock. Blood tests showed hypernatraemia, hyperchloraemia and raised urea and creatinine. Initially, he was treated for dehydration secondary to sepsis. However, high urine output combined with low urine osmolality and high plasma osmolality was suggestive of a disorder of arginine vasopressin (AVP), previously called diabetes insipidus (DI). On further endocrine testing, thyroxine (T4) level was low with an inappropriately normal thyroid-stimulating hormone level with no other anterior pituitary hormone abnormalities, a normal MRI head and ophthalmological assessment. Desmopressin, a synthetic form of AVP, was commenced, however, there was an inadequate response despite dose escalation, leading to a diagnosis of AVP resistance (previously nephrogenic DI) rather than AVP deficiency (previously cranial DI). Copeptin, an AVP precursor peptide and surrogate marker, was significantly elevated. A renal tubulopathy genetic screen demonstrated a likely pathogenic hemizygous variant in the AVP receptor 2 gene, which has previously been associated with X-linked vasopressin resistance. This case demonstrates the challenge of differentiating between AVP deficiency and resistance in infancy and the value of copeptin and genetic testing in confirming diagnosis. We outline an approach to fluid management in AVP disorders.

A targeted gene panel illuminates pathogenesis in young people with unexplained kidney failure.

BACKGROUND: Kidney failure in young people is often unexplained and a significant proportion will have an underlying genetic diagnosis. National Health Service England pioneered a comprehensive genomic testing service for such circumstances accessible to clinicians working outside of genetics. This is the first review of patients using this novel service since October 2021, following its introduction into clinical practice. METHODS: The 'Unexplained Young-Onset End-Stage Renal Disease' (test-code R257) gene panel uses targeted next generation sequencing to analyse 175 genes associated with renal disease in patients under 36 years of age. All tests undertaken between October 2021 and February 2022 were reviewed. Phenotypic data were extracted from request forms and referring clinicians contacted where additional details were required. RESULTS: Seventy-one patients underwent R257 testing over the study period. Among them, 23/71 patients (32%) were confirmed to have a genetic diagnosis and 2/71 (3%) had a genetically suggestive variant. Nephronophthisis and Alport syndrome were the most common conditions identified, (4/23 (17%) with pathogenic variants in NPHP1 and 4/23 (17%) with pathogenic variants in COL4A3/COL4A4). Positive predictors of a genetic diagnosis included a family history of renal disease (60% of positive cases) and extra-renal disease manifestations (48% of positive cases). CONCLUSION: This is the first study to evaluate the R257 gene panel in unexplained young-onset kidney failure, freely accessible to patients meeting testing criteria in England. A genetic diagnosis was identified in 32% of patients. This study highlights the essential and expanding role that genomic testing has for children and families affected by renal disease today.

How to solve a clinical conundrum: Have you tried a trio exome analysis?

The following report describes the clinical journey of a 5-month-old male infant who presented with a significant kidney injury following a diarrhoeal illness. His course was complicated by severe hypertension and a number of acute life-threatening events necessitating periods of time on the intensive care unit, where he received ventilatory support and underwent renal replacement therapy and treatment with a monoclonal antibody therapy.We take the reader on a stepwise journey from presentation through to final diagnosis, discussing important biochemical, haematological and radiological features where learning points are discussed. Guidance on the use of genomic testing strategies for the non-geneticist is provided in some detail with a particular focus on the trio exome analysis that identified the diagnosis for this young boy.This complex case not only provides a number of excellent learning opportunities but also highlights the importance of early involvement of the clinical genetics team and the relevance of the trio exome analysis for rapid identification of rare monogenic diseases.

Pulmonary hypertension in juvenile-onset systemic lupus erythematosus: a case series.

OBJECTIVES: Systemic lupus erythematosus (SLE) is a rare multisystem autoimmune disorder with a variable clinical phenotype. Pulmonary hypertension (PHTN) is a recognised (and not uncommonly asymptomatic) complication of the condition with an associated poor prognosis in adults. It is relatively rare in juvenile-onset SLE (JSLE). METHODS: We present a retrospective descriptive case series of four female children aged 4 to 15 years at presentation of JSLE and aged 8 to 27 years at time of diagnosis of PHTN from the United Kingdom. All cases were identified through the UK JSLE Cohort Study. RESULTS: Of 665 children with JSLE in the UK cohort study to date (data from 2006-2020), four (0.6%) were identified as having PHTN. 3/4 of the PHTN cases presented with cardiovascular symptoms and / or signs at presentation.3/4 were treated with Rituximab and had a good long-term outcome. Shared clinical features include high baseline disease activity scores. CONCLUSIONS: JSLE has a high associated cardiovascular morbidity and mortality and early identification of treatable complications such as PHTN is vital. We suggest that children with high baseline disease activity scores and those presenting with cardiovascular symptoms and signs are most likely to have concurrent PHTN. Routine echocardiography is an effective screening tool and should be used as part of a standard diagnostic work-up.

Paediatric rhabdomyolysis: A UK centre's 10-year retrospective experience.

AIMS: To describe the aetiologies of paediatric rhabdomyolysis and explore the medium-term renal consequences. METHODS: Retrospective, single-centre review of children with rhabdomyolysis. RESULTS: Two hundred and thirty-two children met inclusion criteria for the analysis. Mean age at presentation was 8.4 (SD ± 5.5) years. The commonest aetiology was infection (28%), with viral myositis making up the clear majority (75%). Trauma was identified as a cause in 18% of children, seizures in 10% and immune-mediated mechanisms in 8%. Acute kidney injury (AKI) was present in 32% of the cases overall. Children with AKI tended to be younger, with higher peak creatine kinase (CK) and active urinary sediment on urinalysis at presentation. AKI and the need for renal replacement therapy (RRT) were associated with a prolonged hospital stay (15 (interquartile range, IQR 6.5-33) vs. 2 (IQR 0-7) days). A total of 18 children and young people required RRT, with a mean duration of 7.1 ± 4.3 days. Those who received RRT were more likely to have abnormalities on urinalysis at presentation (46% vs. 5%). Over the period of the study, 9% of children died and 2% met criteria for a diagnosis of chronic kidney disease. CONCLUSIONS: This large paediatric rhabdomyolysis case series provides new and unique insights into the condition. Our results highlight the common aetiologies and provide evidence of good renal recovery overall, even in the most severely affected cases. Abnormalities of urinalysis appear to be important in predicting the development of AKI and the need for RRT.

Peroxisome proliferator activating receptor-γ and the podocyte.

Over the past two decades it has become clear that the glomerular podocyte is a key cell in preventing albuminuria, kidney failure and cardiovascular morbidity. Understanding the key pathways that protect the podocyte in times of glomerular stress, which can also be therapeutically manipulated, are highly attractive. In the following review we assess the evidence that the peroxisome proliferator activating receptor (PPAR) agonists are beneficial for podocyte and kidney function with a focus on PPAR-γ. We explain our current understanding of the mechanisms of action of these agonists and the evidence they are beneficial in diabetic and non-diabetic kidney disease. We also outline why these drugs have not been widely used for kidney disease in the past but they may be in the future.

Implementation of NICE guidance on urinary tract infections in children in primary and secondary care.

AIM: To audit compliance with the 2007 National Institute of Clinical Excellence guidelines on the management of urinary tract infection in children under the age of 16 years across primary and secondary care services in England. METHODS: A retrospective multisite audit of 10 general practice, 3 paediatric, 2 paediatric emergency and 2 emergency general units. Four distinct geographical areas were represented. Data were collected between 1 January 2010 and 31 December 2010. Six criteria were audited, which focused on the following: improving the rate of diagnosis, management of the very young child with UTI and selection of children for imaging. RESULTS: A total of 1149 children were audited (682 from primary care and 467 from secondary care). Overall compliance was as follows: criterion 1: 28%; criterion 2: 68%; criterion 3: 89%; criterion 4: 43%; criterion 5 (comprising 12 subcriteria): 13% and for criterion 6: 45%. CONCLUSION: The results indicate significant shortcomings in the implementation of NICE guidance on childhood UTI in England. The guidance is complex and this makes its implementation challenging. It was difficult to identify children presenting with nonspecific fever from clinical data systems. Adequate IT systems throughout the NHS are a key step to improving implementation of this and other NICE guidance.

Dent's disease complicated by an acute Budd-Chiari syndrome.

We present the case of a young boy with Dent's disease, identified as having a mutation in the kidney-specific chloride-proton antitransporter CLCN5 during investigation for nephrotic-range proteinuria. He went on to develop growth hormone deficiency and was treated with recombinant growth hormone. He later presented acutely with hepatorenal failure and thrombotic occlusion of the middle and right hepatic veins consistent with a diagnosis of Budd-Chiari syndrome, which required a prolonged period of intensive care. The diagnosis of Dent's disease should be considered early in boys with nephrotic-range proteinuria in the absence of clinical oedema and hypoalbuminaemia to allow for the timely introduction of strategies, such as a high-citrate diet, to preserve renal function. The measurement of urinary ß-2 microglobulin has been shown by this case to be a more reliable and specific marker of tubular dysfunction than the urinary retinol-binding protein.

Middle-term use of Cinacalcet in paediatric dialysis patients.

The effects of the calcimimetic drug Cinacalcet were assessed in six children with uncontrolled hyperparathyroidism secondary to stage 5 chronic kidney disease (CKD). Data were collected retrospectively regarding bone biochemistry and medications. Patients were between the ages of 11 months and 14 years on commencing Cinacalcet at initial doses of 0.4-1.4 mg/kg. Treatment, which was well tolerated in the majority and still on going in five patients, was for periods ranging between 3 months and 3 years. All six cases saw at least an 86% reduction in serum parathyroid hormone (PTH). Hypophosphataemia and/or hypocalcaemia were observed in three cases. Overall, achievement of UK Renal Association targets for corrected calcium (Ca), phosphate (P) and the calcium x phosphate product (Ca x P) were unaffected. We conclude that Cinacalcet is an effective treatment for correcting and sustaining correction of uncontrollable PTH levels seen in a difficult group of patients. Importantly, it has allowed the avoidance of parathyroidectomy for a significant time period in all cases. There remain questions about the effect of Cinacalcet on linear growth amongst paediatric dialysis patients, and future studies should aim to address this.