Summary

Barakat syndrome, also called HDR syndrome, is a rare genetic disorder encompassing hypoparathyroidism (H), sensorineural deafness (D) and renal disease (R). A 64-year-old woman was referred to our endocrinology clinic for a switch in treatment (from dihydrotachysterol to calcitriol). She had progressive sensorineural deafness since the age of 18 and idiopathic hypoparathyroidism diagnosed at age of 36. Her medical history included osteoporosis with hip/spine fractures, nephrolithiasis and a family history of hearing loss, osteoporosis and kidney disease. The patient’s clinical presentation indicated Barakat syndrome. Genetic analysis found a GATA3:c.916C>T nonsense variant. Further tests such as audiometry, labs and renal imaging supported the diagnosis. Due to rarity and manifold symptoms, diagnosis can be challenging. Optional GATA3 testing was suggested in 2018, except in cases of isolated sensorineural deafness or renal disease with pertinent family history. In isolated ‘H’ cases without ‘D’ and ‘R’, GATA3 studies are not required, as no haploinsufficiency cases were reported. Given the rise in genetic disorders, physicians should consistently consider rare genetic disorders in patients with suggestive symptoms, even decades after onset. Although diagnosis might not always impact management directly, it aids patients in accepting their condition and has broader family implications.

Learning points

• There is currently an important increase in genetic and clinical characterization of new orphan diseases and their causative agents.

• Unbiased re-evaluation for possible genetic disorders is necessary at every consultation.

• It is essential to recognize the differential diagnosis of idiopathic hypoparathyroidism.

• The patient’s clinical presentation and family history can be important to establish the correct diagnosis.

• Physicians should not hesitate to search a patient’s signs and symptoms online.

Summary

Fibromuscular dysplasia can cause renovascular hypertension. Since fibromuscular dysplasia may be underdiagnosed, precise diagnosis and management are crucial, especially for young women. A 20-year-old woman with hypertension and hypokalemia was referred to our hospital for further evaluation of secondary hypertension. At the previous hospital, her blood pressure was 160/110 mmHg and the serum potassium level was 2.9 mEq/L. The equilibrium phase on contrast-enhanced computed tomography revealed a low-density area in the upper median portion of the right kidney. On admission to our hospital, her blood pressure was 141/96 mmHg under 5 mg of amlodipine. Laboratory tests revealed plasma renin activity of 11.3 ng/mL/h and plasma aldosterone concentration of 117.1 pg/mL. Renal venous sampling of active renin concentration showed a right-to-left renin ratio of 3.13, confirming a significant increase in renin secretion from the right kidney. Selective reno-angiography detected focal stenosis with adjacent aneurysmal dilation and tortuosity in the proximal branch of the right renal artery. She was diagnosed with branch artery fibromuscular dysplasia and successfully treated with percutaneous transluminal angioplasty. After the treatment, she was free from hypertension and hypokalemia without any medications. Since branch artery fibromuscular dysplasia is sometimes difficult to diagnose, contrast-enhanced computed tomography can be a promising diagnostic tool as shown in this case. Concerning treatment, our patient was treated with percutaneous transluminal angioplasty, which should be considered for women of reproductive age because recommended antihypertensive medications can be teratogenic even in the first trimester of pregnancy.

Learning points

• Although branch artery fibromuscular dysplasia (FMD) is sometimes difficult to diagnose, it should be considered in patients with high-renin, high-aldosterone hypertension.

• Branch artery FMD can present with a low-density area of the kidney on contrast-enhanced computed tomography, as shown in this case.

• Percutaneous transluminal angioplasty (PTA) can be an appropriate treatment for branch artery FMD, especially in young female patients.

• PTA may immediately improve hypertension and hypokalemia without the need for medications.

Summary

Triglyceride deposit cardiomyovasculopathy (TGCV) is an intractable disease characterized by massive triglyceride (TG) accumulation in the myocardium and coronary arteries caused by genetic or acquired dysfunction of adipose TG lipase (ATGL). A phase IIa trial has been conducted involving patients with idiopathic TGCV using CNT-01 (tricaprin/trisdecanoin) by the Japan TGCV study group, which showed that CNT-01 improved myocardial lipolysis as demonstrated by iodine-123-beta-methyl iodophenyl-pentadecanoic acid (BMIPP) scintigraphy. We evaluated changes in myocardial TG content using proton magnetic resonance spectroscopy (¹H-MRS) before/after CNT-01. This report describes a male patient with hypertension, diabetes, angina pectoris, repeated percutaneous coronary intervention, chest pain, and exertional dyspnea that persisted despite standard medications and nitroglycerin. Idiopathic TGCV was diagnosed based on a remarkably reduced washout rate (WR) for BMIPP scintigraphy, high myocardial TG content on ¹H-MRS, and no ATGL mutation. After an 8-week, 1.5 g/day CNT-01 administration, the WR of BMIPP increased from 5.1 to 13.3% and the myocardial TG content decreased from 8.4 to 5.9%, with no adverse effects. CNT-01 corrected myocardial lipolysis and subsequently reduced TG content in idiopathic TGCV as evaluated using ¹H-MRS, which may be a useful, noninvasive evaluation of therapeutic efficacy.

Learning points

• Triglyceride deposit cardiomyovasculopathy (TGCV) is an intractable disease characterized by massive triglyceride accumulation in the myocardium and coronary arteries, caused by genetic or acquired dysfunction of adipose triglyceride lipase.

• Japan TGCV Study Group developed a specific treatment for idiopathic TGCV using CNT-01 (tricaprin/trisdecanoin), a type of medium-chain fatty acid.

• CNT-01 corrected myocardial lipolysis and reduced TG content in idiopathic TGCV using proton magnetic resonance spectroscopy, which may be a useful noninvasive evaluation of therapeutic efficacy.

Summary

Depot medroxyprogesterone acetate, also known as Depo-Provera, is a progesterone-only contraceptive that is administered by injection to patients every three months. We describe the case of a 19-year-old female who was diagnosed with central diabetes insipidus following the administration of the contraceptive injection Depo-Provera. The patient was diagnosed with polycystic ovarian syndrome at age 16 and was originally prescribed oral contraceptives to restore menstrual regularity. Three years later, Depo-Provera was substituted for convenience, and symptoms of polyuria and polydipsia appeared one month after initiating the progesterone-only regimen. We are proposing that central diabetes insipidus may be a possible adverse effect of Depo-Provera in women with polycystic ovarian syndrome who receive the progesterone-only contraception, due to the interference of their arginine vasopressin mechanism through the alteration of estrogen levels. We review potential mechanisms through the presentation of previously completed research in polycystic ovarian syndrome.

Learning points

• We propose that although rare, the decrease in estrogen that is experienced during the administration of Depo-Provera can interfere with arginine vasopressin release in patients with polycystic ovarian syndrome (PCOS).

• Increased awareness of possible lasting adverse effects on fluid balance with unopposed progesterone administration in PCOS is important, as this case of the development of diabetes insipidus suggests.

• Discussion of such potential side effects is important when considering contraceptive options for the regulation of menses in patients with PCOS.

Learning points

• Nodular glomerular lesions in diabetes mellitus are thought to be associated with long-term severe hyperglycemia.

• This case shows that although mild, long-term hyperglycemia for more than 10 years may also contribute to the formation of nodular lesions and that repeated chronic kidney infections over the years and chronic acidosis may be facilitating factors in the formation of diabetic nephropathy, including nodular glomerular lesions.

• This case appears to be idiopathic nodular glomerulosclerosis of the medullary sponge kidney associated with chronic urinary tract infection.

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.

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.

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.

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

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.