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Open access

Canagliflozin-associated severe hyponatremia: a rare and potentially adverse effect?

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.

DOI:
https://doi.org/10.1530/EDM-21-0035
Volume 2022: Issue 1
Open access

Juxtaglomerular cell tumour of the kidney: a rare cause of resistant hypertension

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.

DOI:
https://doi.org/10.1530/EDM-21-0042
Volume 2022: Issue 1
Open access

Infantile hypercalcaemia type 1: a vitamin D-mediated, under-recognised cause of hypercalcaemia

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

DOI:
https://doi.org/10.1530/EDM-21-0058
Volume 2021: Issue 1
Open access

A rare case of ectopic ACTH syndrome caused by primary renal neuroendocrine tumor

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.

DOI:
https://doi.org/10.1530/EDM-20-0076
Volume 2021: Issue 1
Open access

A case of Carney triad complicated by renal cell carcinoma and a germline SDHA pathogenic variant

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.

DOI:
https://doi.org/10.1530/EDM-20-0170
Volume 2021: Issue 1
Open access

Intermixed medullary and papillary thyroid cancer in a patient with renal cell carcinoma

Shanika Samarasinghe, Simge Yuksel, and Swati Mehrotra

Summary

We report a rare case of concurrent medullary thyroid cancer (MTC) and papillary thyroid cancer (PTC) with intermixed disease in several of the lymph node (LN) metastases in a patient who was subsequently diagnosed with clear cell renal cell carcinoma (RCC). A 56 year old female presented with dysphagia and was found to have a left thyroid nodule and left superior cervical LN with suspicious sonographic features. Fine needle aspiration biopsy (FNAB) demonstrated PTC in the left thyroid nodule and MTC in the left cervical LN. Histopathology demonstrated multifocal PTC with 3/21 LNs positive for metastatic PTC. One LN in the left lateral neck dissection exhibited features of both MTC and PTC within the same node. In the right lobe, a 0.3 cm focus of MTC with extra-thyroidal extension was noted. Given persistent calcitonin elevation, a follow-up ultrasound displayed an abnormal left level 4 LN. FNAB showed features of both PTC and MTC on the cytopathology itself. The patient underwent repeat central and left radical neck dissection with 3/6 LNs positive for PTC in the central neck and 2/6 LNs positive for intermixed PTC and MTC in the left neck. There was no evidence of distant metastases on computed tomography and whole body scintigraphy, however a 1.9 x 2.5 cm enhancing mass within the right inter-polar kidney was discovered. This lesion was highly suspicious for RCC. Surgical pathology revealed a 2.5 cm clear cell RCC, Fuhrman grade 2/4, with negative surgical margins. She continues to be observed with stable imaging of her triple malignancies.

Learning points:

  • Mixed medullary-papillary thyroid neoplasm is characterized by the presence of morphological and immunohistochemical features of both medullary and papillary thyroid cancers within the same lesion. Simultaneous occurrence of these carcinomas has been previously reported, but a mixed disease within the same lymph node is an infrequent phenomenon.

  • Prognosis of mixed medullary-papillary thyroid carcinomas is determined by the medullary component. Therefore, when PTC and MTC occur concurrently, the priority should be given to the management of MTC, which involves total thyroidectomy and central lymph node dissection.

  • Patients with thyroid cancer, predominantly PTC, have shown higher than expected rates of RCC. To our knowledge, this is the first report describing the combination of MTC, PTC, and RCC in a single patient.

DOI:
https://doi.org/10.1530/EDM-20-0025
Volume 2020: Issue 1
Open access

Milk-alkali syndrome: a ‘quick ease’ or a ‘long-lasting problem’

Mawson Wang, Catherine Cho, Callum Gray, Thora Y Chai, Ruhaida Daud, and Matthew Luttrell

Summary

We report the case of a 65-year-old female who presented with symptomatic hypercalcaemia (corrected calcium of 4.57 mmol/L) with confusion, myalgias and abdominal discomfort. She had a concomitant metabolic alkalosis (pH 7.46, HCO3 - 40 mmol/L, pCO2 54.6 mmHg). A history of significant Quick-Eze use (a calcium carbonate based antacid) for abdominal discomfort, for 2 weeks prior to presentation, suggested a diagnosis of milk-alkali syndrome (MAS). Further investigations did not demonstrate malignancy or primary hyperparathyroidism. Following management with i.v. fluid rehydration and a single dose of i.v. bisphosphonate, she developed symptomatic hypocalcaemia requiring oral and parenteral calcium replacement. She was discharged from the hospital with stable biochemistry on follow-up. This case demonstrates the importance of a detailed history in the diagnosis of severe hypercalcaemia, with MAS representing the third most common cause of hypercalcaemia. We discuss its pathophysiology and clinical importance, which can often present with severe hypercalcaemia that can respond precipitously to calcium-lowering therapy.

Learning points:

  • Milk-alkali syndrome is an often unrecognised cause for hypercalcaemia, but is the third most common cause of admission for hypercalcaemia.

  • Calcium ingestion leading to MAS can occur at intakes as low as 1.0–1.5 g per day in those with risk factors.

  • Early recognition of this syndrome can avoid the use of calcium-lowering therapy such as bisphosphonates which can precipitate hypocalcaemia.

DOI:
https://doi.org/10.1530/EDM-20-0028
Volume 2020: Issue 1
Open access

Licorice induced pseudohyperaldosteronism, severe hypertension, and long QT

Stine Bech Smedegaard and Mads Vandsted Svart

Summary

Excessive intake of licorice may cause pseudohyperaldosteronism which, in turn, may lead to hypertension and hypokalemia. Severe hypokalemia may lead to electrocardiogram (ECG) changes including long QT interval potentially progressing into malignant arrhythmias. Here we present a 43-year-old woman admitted to the hospital with chest pain and a stinging sensation in the upper extremities. Her peak blood pressure was 177/98 mmHg and the blood test revealed low plasma potassium of 1.9 mmol/L. The ECG revealed flattened T-waves and long QT interval. Prior to admission, the patient had increased licorice ingestion to a total of some 70 g daily. The licorice intake was stopped and potassium was administrated orally and intravenously. Plasma potassium normalized and the ECG changes remitted. To our knowledge a few other cases of licorice-induced pseudohyperaldosteronism and long QT interval have previously been reported. This underlines the importance of quantifying licorice intake in younger people with unexplained high blood pressure and low potassium.

Learning points:

  • Even small amounts of licorice daily may increase the risk of developing hypertension; therefore, licorice should be asked for specifically.

  • Even though licorice intake is very easy to cover in the patient’s history, it is often missed.

  • Excessive licorice intake may course severe hypokalemia causing long QT interval in the ECG recording, potentially progressing into arrhythmias and even cardiac arrest/sudden death.

  • Hypokalemia <3 mmol/L and present ECG changes should be treated with potassium intravenously.

  • Licorice-induced hypertension may be associated with syndrome of apparent mineralocorticoid excess (SAME). Plasma renin and aldosterone are both low at diagnosis and normalize when licorice is stopped.

DOI:
https://doi.org/10.1530/EDM-19-0109
Volume 2019: Issue 1
Open access

A case of type B insulin resistance syndrome treated with low-dose glucocorticoids

Masato Kotani, Naohisa Tamura, Tatsuhide Inoue, and Issei Tanaka

Summary

Type B insulin resistance syndrome is characterized by the presence of autoantibodies to the insulin receptor. We present a 57-year-old male admitted to a hospital due to body weight loss of 16 kg and hyperglycemia of 13.6 mmol/L. He was diagnosed with type B insulin resistance syndrome because the anti-insulin receptor antibodies were positive. We informed him that some hyperglycemic cases of this syndrome had been reported to be spontaneously remitted in 5 years, and he did not agree to be treated with high-dose glucocorticoids and/or immunosuppressive agents due to his concern for their adverse effects such as hyperglycemia and immunosuppression. He chose to be treated with insulin and voglibose, but fair glucose control could not be obtained. Six years later, he agreed to be treated with low-dose glucocorticoids practicable in outpatient settings. One milligram per day of betamethasone was tried orally and reduced gradually according to the values of glycated hemoglobin. After 30 months of glucocorticoid treatment, the anti-insulin receptor antibodies became undetectable and his fasting plasma glucose and glycated hemoglobin were normalized. This case suggests that low-dose glucocorticoids could be a choice to treat type B insulin resistance syndrome in outpatient settings.

Learning points:

  • Type B insulin resistance syndrome is an acquired autoimmune disease for insulin receptors.

  • This case suggested the possibility of long-lasting, low-dose glucocorticoid therapy for the syndrome as an alternative for high-dose glucocorticoids or immunosuppressive agents.

  • Since the prevalence of autoimmune nephritis is high in the syndrome, a delay of immunosuppressive therapy initiation might result in an exacerbation of nephropathy.

DOI:
https://doi.org/10.1530/EDM-19-0115
Volume 2019: Issue 1
Open access

Significant polar vasculosis in a patient with a 30-year history of type 2 diabetes

Yasuhiro Oda, Masayuki Yamanouchi, Hiroki Mizuno, Rikako Hiramatsu, Tatsuya Suwabe, Junichi Hoshino, Naoki Sawa, Kenichi Ohashi, Takeshi Fujii, and Yoshifumi Ubara

Summary

We report the renal histology of a 66-year-old man with hypertension, cardiovascular disease, and a 30-year history of type 2 diabetes mellitus with proliferative diabetic retinopathy, diabetic neuropathy, and diabetic foot status post toe amputation. Urinary protein excretion was 1.4 g/gCr, serum creatinine level 0.86 mg/dL, estimated glomerular filtration rate 69 mL/min/1.73 m2, and HbA1c 13–15%, despite using insulin. Light microscopy showed global glomerulosclerosis in 37% of the glomeruli, but the remaining glomeruli were intact. Significant polar vasculosis was present, while arteriolar sclerosis was mild. Electron microscopy revealed a thickened glomerular basement membrane, which is compatible with the early stage of diabetic glomerulopathy. The presented case was unique because glomerular changes seen typically in diabetes were not seen in the patient, despite the long-standing history of diabetes and diabetic comorbidities, while prominent polar vasculosis was found. Polar vascular formation helps preserve the glomeruli by allowing hyperosmotic blood bypass the glomeruli; this decreases intraglomerular pressure and minimizes glomerular endothelial damage.

Learning points:

  • A 66-year-old man with a 30-year history of type 2 diabetes mellitus with poor glycemic control underwent renal biopsy, which showed scarce glomerular changes typically seen in diabetic kidney disease and instead revealed significant polar vasculosis.

  • Past studies demonstrated that the increased small vessels around the vascular hilus in diabetic patients originated from the afferent arterioles and drained into the peritubular capillaries.

  • Polar vascular formation may preserve glomerular function by allowing the blood flow to bypass the glomeruli and decreasing the intraglomerular pressure, which minimizes endothelial damage of the glomerular tufts.

DOI:
https://doi.org/10.1530/EDM-19-0092
Volume 2019: Issue 1