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Open access

Maheswaran Dhanasekaran, Siddharth Narayanan, Ioannis Mastoris, and Suchita Mehta

Summary

Sodium-glucose cotransporter-2 inhibitors (SGLT2i) induce osmotic diuresis by inhibiting the proximal renal tubular reabsorption of the filtered glucose load, which in turn can occasionally lead to severe dehydration and hypotension amidst other adverse effects. We present a case of a 49-year-old man with type 2 diabetes mellitus (T2D) on canagliflozin, a SGLT2i. The patient was brought to the emergency room following a motor vehicle accident. He was confused and had an altered mental status. His blood alcohol and urine toxicology screens were negative. Initial investigations revealed that he had severe hyponatremia with euglycemic ketoacidosis. The adverse condition was reversed with close monitoring and timely management, and the patient was eventually discharged. This is the first report to suggest hyponatremia as a potentially serious adverse effect following SGLT2i therapy. Its impact on the renal tubule handling of sodium and water is not yet well characterized. While further studies are warranted to understand better the pathophysiological mechanisms associated with SGLT2i-induced adverse effects, timely dose reduction or perhaps even its temporary discontinuation may be recommended to prevent complications.

Learning points

  • Sodium-glucose cotransporter-2 inhibitors (SGLT2i) are usually well-tolerated, but some serious adverse effects have been documented.

  • Our case report suggests hyponatremia as a potential, rare side effect of SGLT2i and makes physicians aware of the occurrence of such life-threatening but preventable complications.

  • Timely and close monitoring of the patient, with temporary discontinuation of this drug, may be recommended towards effective management.

  • Studies demonstrating a comprehensive understanding of SGLT2i-related electrolyte derangements are warranted.

Open access

N Ayub, A J A T Braat, H J L M Timmers, M G E H Lam, and R S van Leeuwaarde

Summary

Von Hippel–Lindau’s disease (VHL) is a hereditary tumor syndrome characterized by its prototype lesions, hemangioblastomas, and renal cell carcinomas. Treatment for renal cell carcinomas can ultimately result in long-term dialysis. Pancreatic neuroendocrine tumors (pNET) can also occur in the course of the disease. Currently, peptide receptor radionuclide therapy (PRRT) is the standard treatment for progressive neuroendocrine tumors. However, little is known about treatment with PRRT in patients on dialysis, an infrequent presentation in patients with VHL. We present a 72-year-old man with VHL on hemodialysis and a progressive pNET. He received four cycles of PRRT with a reduced dose. Only mild thrombopenia was seen during treatments. The patient died 9 months after the last PRRT because of acute bleeding in a hemangioblastoma. Hemodialysis is not a limiting factor for PRRT treatment and it should be considered as it seems a safe short-term treatment option for this specific group.

Learning points

  • Von Hippel–Lindau disease (VHL) is a complex disease in which former interventions can limit optimal treatment for following VHL-related tumors later in life.

  • Metastasized pancreatic neuroendocrine tumors occur as part of VHL disease.

  • Peptide receptor radionuclide therapy seems a safe short-term treatment option in patients on hemodialysis.

Open access

Nikitas S Skarakis, Irene Papadimitriou, Labrini Papanastasiou, Sofia Pappa, Anastasia Dimitriadi, Ioannis Glykas, Konstantinos Ntoumas, Penelope Lampropoulou, and Theodora Kounadi

Summary

Juxtaglomerular cell tumour (JGCT) is an unusually encountered clinical entity. A 33-year-old man with severe long-standing hypertension and hypokalaemia is described. The patient also suffered from polyuria, polydipsia, nocturia and severe headaches. On admission, laboratory investigation revealed hypokalaemia, kaliuresis, high aldosterone and renin levels, and the abdomen CT identified a mass of 4 cm at the right kidney. Kidney function was normal. Following nephrectomy, the histological investigation revealed the presence of a JGCT. Immunostaining was positive for CD34 as well as for smooth muscle actin and vimentin. Following surgery, a marked control of his hypertension with calcium channel blockers and normalization of the serum potassium, renin or aldosterone levels were reached. According to our findings, JGCT could be included in the differential diagnosis of secondary hypertension as it consists of a curable cause. The association of JGCT with hypertension and hypokalaemia focusing on the clinical presentation, diagnostic evaluation and management is herein discussed and a brief review of the existing literature is provided.

Learning points

  • Juxtaglomerular cell tumours (JGCT), despite their rarity, should be included in the differential diagnosis of secondary hypertension as they consist of a curable cause of hypertension.

  • JGCT could be presented with resistant hypertension along with hypokalaemia, kaliuresis and metabolic alkalosis. Early recognition and management can help to prevent cardiovascular complications.

  • Imaging (enhanced CT scans) may be considered as the primary diagnostic tool for the detection of renal or JGCT.

  • For the confirmation of the diagnosis, a histopathologic examination is needed.

Open access

Ryizan Nizar, Nathan W P Cantley, and Jonathan C Y Tang

Summary

A 33-year-old gentleman of Egyptian heritage presented with a 21 years history of unexplained and recurrent hypercalcaemia, nephrolithiasis, nephrocalcinosis, and myocarditis. A similar history was also found in two first-degree relatives. Further investigation into the vitamin D metabolism pathway identified the biochemical hallmarks of infantile hypercalcaemia type 1 (IIH). A homozygous, likely pathogenic, variant in CYP24A1 was found on molecular genetic analysis confirming the diagnosis. Management now focuses on removing excess vitamin D from the metabolic pathway as well as reducing calcium intake to achieve serum-adjusted calcium to the middle of the reference range. If undiagnosed, IIH can cause serious renal complications and metabolic bone disease.

Learning points

  • Infantile hypercalcaemia type 1 (IIH) is an autosomal recessive disorder characterised by homozygous mutations in the CYP24A1 gene that encodes the 24-hydroxylase enzyme used to convert active vitamin D metabolites such as 1,25-(OH)2-vitamin D into their inactive form.

  • IIH should be questioned in individuals presenting with a history of unexplained hypercalcaemia, especially if presenting from childhood and/or where there is an accompanying family history of the same in first and/or second degree relatives, causing complications such as nephrocalcinosis, pericarditis, and calcium-based nephrolithiasis.

  • Associated biochemistry of IIH is persistent mild to moderate hypercalcaemia, normal or raised 25-(OH)-vitamin D and elevated 1,25-(OH)2-vitamin D. An elevated ratio of 25-(OH)-vitamin D to 24,25-(OH)2-vitamin D can be a useful marker of defects in the 24-hydroxylase enzyme, whose measurement can be facilitated through the supra-regional assay service.

  • Management should focus on limiting the amount of vitamin D introduced into the body either via sunlight exposure or supplementation in addition to calcium dietary restriction to try and maintain appropriate calcium homeostasis

Open access

Ayesha Ghayur, Qurrat Elahi, Chinmay Patel, and Rishi Raj

Summary

Hypothyroidism is a common medical condition and is often easily managed with excellent outcomes, when treated adequately. Compliance with levothyroxine (LT4) therapy is often compromised because of the need for a daily and lasting schedule. Overt rhabdomyolysis due to under-treatment or non-compliance is a rare occurrence. We report a case of rhabdomyolysis leading to acute kidney injury (AKI) on chronic kidney disease (CKD) requiring hemodialysis (HD) in a 68-year-old Caucasian male due to non-compliance with levothyroxine (LT4) therapy. Our patient 'ran out of levothyroxine' for approximately 4 weeks and developed gradually progressive muscle pain. The diagnosis of severe AKI due to rhabdomyolysis was made based on oliguria, elevated creatinine kinase (CK), and renal failure. Resuming the home dose of LT4 failed to correct CK levels, and there was a progressive decline in renal function. Although increasing doses of LT4 and three cycles of HD improved CK levels, they remained above baseline at the time of discharge. The patient recovered gradually and required HD for 4 weeks. CK levels normalized at 6 weeks. Through this case report, we highlight that non-compliance with LT4 therapy can lead to life-threatening complications such as renal failure and hence the need to educate patients on the significance of compliance with LT4 therapy should be addressed.

Learning points

  • Non-compliance to levothyroxine therapy is common and can lead to serious complications, including rhabdomyolysis.

  • Rhabdomyolysis is an uncommon presentation of hypothyroidism and severe rhabdomyolysis can result in renal failure requiring hemodialysis.

  • Rhabdomyolysis associated with hypothyroidism can be further exacerbated by concomitant use of statins.

Open access

Paweena Chunharojrith, Kanapon Pradniwat, and Tanawan Kongmalai

Summary

Ectopic adrenocorticotropic hormone (ACTH) secretion is responsible for 5–15% of Cushing’s syndrome (CS). Neuroendocrine tumor (NET) is a common cause of ectopic ACTH syndrome (EAS). However, primary renal NET is exceedingly rare. Fewer than 100 cases have been reported and only a few cases presented with CS. Because of its rarity and lack of long-term follow-up data, clinical manifestations, biological behavior and prognosis are not well understood. Here, we report the case of a 51-year-old man who presented with clinical and laboratory findings compatible with EAS. CT scan revealed a lesion of uncertain nature at the lower pole of the left kidney. Octreotide scan found a filling defect at the lower pole of left kidney. It was difficult to determine if this finding was the true etiology or an incidental finding. Unfortunately, the patient’s clinical status rapidly deteriorated with limited medical treatment. The patient underwent left nephrectomy and left adrenalectomy. Histopathological examination confirmed NET with oncocytic features. Immunohistochemistry staining was positive for ACTH. The patient’s condition gradually improved. Additionally, glucocorticoid replacement was required only 6 months during a gradual recovery of hypothalamic pituitary adrenal axis achieved approximately three years after tumor removal. Although extremely rare, primary renal NET should be considered as a cause of EAS particularly in a patient with rapid clinical deterioration. Thorough investigation, early diagnosis and careful management are crucial to reduce morbidity and mortality.

Learning points

  • Primary renal NET is an extremely rare cause of ectopic ACTH syndrome.

  • Ectopic ACTH syndrome has a rapid onset with severe clinical manifestations. In this case, the patient’s condition deteriorated rapidly, resulting from severe hypercortisolism. Resection of the tumor is the most effective treatment.

  • Localization of ectopic ACTH-secreting tumors is very challenging. Multimodality imaging including CT, MRI, octreotide scan, and positron emission tomography plays a crucial role in identifying the tumors. However, each imaging modality has limitations.

Open access

Katsuo Tao, Midori Awazu, Misa Honda, Hironori Shibata, Takayasu Mori, Shinichi Uchida, Tomonobu Hasegawa, and Tomohiro Ishii

Summary

We report a male infant with congenital nephrogenic diabetes insipidus (NDI) who presented with hypercalcemia and hyperphosphatemia since birth. Serum sodium started to increase at 39 days. Although there was no polyuria, urine osmolality was 71 mOsm/kg, when serum osmolality was 296 mOsm/kg with plasma arginine vasopressin 22.5 pg/mL. He was thus diagnosed as NDI. An undetectable level of urine calcium and unsuppressed intact parathyroid hormone suggested hyperparathyroidism including calcium-sensing receptor mutations that could cause hypercalcemia-induced NDI. Polyuria became apparent after the initiation of i.v. infusion for the treatment of hypernatremia. Low calcium and low sodium formula with hypotonic fluid infusion did not correct hypernatremia, hypercalcemia, or hyperphosphatemia. Hydrochlorothiazide and subsequently added celecoxib effectively decreased urine output and corrected electrolytes abnormalities. Normal serum electrolytes were maintained after the discontinuation of low calcium formula. The genetic analysis revealed a large deletion of the arginine vasopressin receptor-2 (AVPR2) gene but no pathogenic variant in the calcium-sensing receptor (CASR) gene. Whether hypercalcemia and hyperphosphatemia were caused by dehydration alone or in combination with other mechanisms remains to be clarified.

Learning points

  • Congenital NDI can present with neonatal hypercalcemia and hyperphosphatemia.

  • Hypercalcemia and hyperphosphatemia can be treated with low calcium and low sodium formula, hydration, hydrochlorothiazide, and celecoxib.

  • Genetic testing is sometimes necessary in the differentiating diagnosis of hypercalcemia associated with NDI.

Open access

Jean Marc Mizzi, Christopher Rizzo, and Stephen Fava

Summary

An 82-year-old female was admitted to a general hospital due to progressive bilateral lower limb weakness. A T8–T9 extramedullary meningioma was diagnosed by MRI, and the patient was referred for excision of the tumour. During the patient’s admission, she was noted to have persistent hyperkalaemia which was refractory to treatment. Following a review by an endocrinology team, a diagnosis of pseudohyperkalaemia secondary to thrombocytosis was made. This case demonstrates the importance of promptly identifying patients who are susceptible to pseudohyperkalaemia, in order to prevent its potentially serious consequences.

Learning points

  • Pseudohyperkalaemia should be considered in patients with unexplained or asymptomatic hyperkalaemia. It should also be considered in those patients who are resistant to the classical treatment of hyperkalaemia.

  • A diagnosis of pseudohyperkalaemia is considered when there is a difference of >0.4 mmol/L of potassium between serum and plasma potassium in the absence of symptoms and ECG changes.

  • In patients who are presenting with consistently elevated serum potassium levels, it may be beneficial to take venous blood gas and/ or plasma potassium levels to rule out pseudohyperkalaemia.

  • Pseudohyperkalaemia may subject patients to iatrogenic hypokalaemia which can be potentially fatal.

  • Pseudohyperkalaemia can occur secondary to thrombocytosis, red cell haemolysis due to improper blood letting techniques, leukaemia and lymphoma.

Open access

Rachel Wurth, Abhishek Jha, Crystal Kamilaris, Anthony J Gill, Nicola Poplawski, Paraskevi Xekouki, Martha M Quezado, Karel Pacak, Constantine A Stratakis, and Fady Hannah-Shmouni

Summary

Succinate dehydrogenase deficiency has been associated with several neoplasias, including renal cell carcinoma (RCC) and those associated with hereditary paraganglioma (PGL)/ pheochromocytoma (PHEO) syndromes, Carney dyad, and Carney triad. Carney triad is a rare multitumoral syndrome characterized by co-existing PGL, gastrointestinal stromal tumor (GIST), and pulmonary chondroma (CHO). We report a case of a 57-year-old male who presented with para-aortic and gastroesophogeal masses, and a right renal superior pole lesion, which were classified as multiple PGLs, a GIST, and a clear cell renal carcinoma, respectively, on pathology following surgical resection. Additionally, a CHO was diagnosed radiologically, although no biopsy was performed. A diagnosis of Carney triad was made. SDHB immunohistochemical staining was negative for the PGL and the GIST, indicating SDH-deficiency. Interestingly, the renal cell carcinoma (RCC) stained positive for both SDHB and SDHA. Subsequent genetic screening of SDH subunit genes revealed a germline inactivating heterozygous SDHA pathogenic variant (c.91 C>T, p.R31X). Loss of heterozygosity was not detected at the tumor level for the RCC, which likely indicated the SDHA variant would not be causative of the RCC, but could still predispose to the development of neoplasias. To the knowledge of the authors this is the first reported case of an SDHA pathogenic variant in a patient with Carney triad complicated by RCC.

Learning points

  • The succinate dehydrogenase enzyme is encoded by four subunit genes (SDHA, SDHB, SDHC, and SDHD; collectively referred to as SDHx), which have been implicated in several neoplasias and are classified as tumor suppressor genes.

  • Carney triad is a rare multiple-neoplasia syndrome presenting as an association of PGLs, GISTs, and CHOs.

  • Carney triad is most commonly associated with hypermethylation of SDHC as demonstrated in tumor tissue, but approximately 10% of cases are due to pathogenic SDHx variants.

  • Although SDHB pathogenic variants are most commonly reported in SDH-deficient renal cell carcinoma, SDHA disease-causing variants have been reported in rare cases.

Open access

Shunsuke Shimazaki, Itsuro Kazukawa, Kyoko Mori, Makiko Kihara, and Masanori Minagawa

Summary

Ammonium acid urate (AAU) crystals are rare in industrialized countries. Furthermore, the number of children with diabetic ketoacidosis (DKA) who develop severe acute kidney injury (AKI) after hospitalization is small. We encountered two patients with AKI caused by AAU crystals during the recovery phase of DKA upon admission. They were diagnosed with severe DKA and hyperuricemia. Their urine volume decreased and AKI developed several days after hospitalization; however, acidosis improved in both patients. Urine sediment analysis revealed AAU crystals. They were treated with urine alkalization and diuretics. Excretion of ammonia in the urine and urine pH levels increased after treatment of DKA, which resulted in the formation of AAU crystals. In patients with severe DKA, the urine and urine sediment should be carefully examined as AAU can form in the recovery phase of DKA.

Learning points:

  • Ammonium acid urate crystals could be formed in the recovery phase of diabetic ketoacidosis.

  • Diabetic ketoacidosis patients may develop acute kidney injury caused by ammonium acid urate crystals.

  • Urine and urine sediment should be carefully checked in patients with severe DKA who present with hyperuricemia and volume depletion.