Salivary Cortisol Response to ACTH Stimulation Is a Reliable Alternative to Serum Cortisol in Evaluating Hypoadrenalism.

CONTEXT: The serum total cortisol response to the ACTH stimulation test is widely used to assess adrenocortical function but is affected by changes in cortisol-binding globulin (CBG) concentration. Salivary cortisol reflects free cortisol concentrations and may offer a reliable alternative. OBJECTIVES: (1) To establish the salivary cortisol response to ACTH stimulation in healthy volunteers and patients with altered CBG concentrations; (2) to evaluate the performance of a lower reference limit (LRL) determined in healthy volunteers in patients with suspected hypoadrenalism (SH-patients). DESIGN: A 250 µg ACTH stimulation test was undertaken in 139 healthy volunteers, 24 women taking an estradiol-containing oral contraceptive pill (OCP-females), 10 patients with low serum protein concentration (LP-patients), and 30 SH-patients. Salivary cortisol was measured by liquid chromatography-tandem mass spectrometry. Mean and LRL of the 30-minute salivary cortisol response (mean-1.96 standard deviation) were derived from log-transformed concentrations. The LRL was applied as a diagnostic cut-off in SH-patients, with comparison to the serum response. RESULTS: Mean CBG concentrations (range) were 58 (42-81) mg/L, 64 (43-95) mg/L, 41 (28-60) mg/L, and 116 (84-159) mg/L in males, females, LP-patients, and OCP-females, respectively. The mean 30-minute salivary cortisol concentration was 19.3 (2.5th-97.5th percentile 10.3-36.2) nmol/L in healthy volunteers. Corresponding values were not different in OCP-females [19.7 (9.5-41.2) nmol/L; P = .59] or LP-patients [19.0 (7.7-46.9) nmol/L; P = .97]. Overall diagnostic agreement between salivary and serum responses in SH-patients was 79%. CONCLUSION: Salivary cortisol response to ACTH stimulation offers a reliable alternative to serum and may be especially useful in conditions of altered CBG concentration.

Evaluating renin and aldosterone levels in children with organic acidemia-therapeutic experience with fludrocortisone.

Hyporeninemic hypoaldosteronism has been reported in only a few cases with methylmalonic acidemia (MMA) and has been attributed to the renal involvement. This study aims to investigate renin-aldosterone levels along with the renal functions of the patients with organic acidemia. This is a cross-sectional study conducted in patients with MMA, propionic acidemia (PA), and isovaleric acidemia (IVA). Serum renin, aldosterone, sodium, and potassium levels were measured, and glomerular filtration rates (GFR) were calculated. Comparisons were made between the MMA and non-MMA (PA+IVA) groups. Thirty-two patients (MMA:PA:IVA = 14:13:5) were included. The median GFR was significantly lower in the MMA group than in the non-MMA group (p < 0.001). MMA patients had the highest incidence of kidney damage (71.4%), followed by PA patients (23%), while none of the IVA patients had reduced GFR. GFR positively correlated with renin levels (p = 0.015, r = 0.433). Although renin levels were significantly lower in the MMA group than the non-MMA group (p = 0.026), no significant difference in aldosterone levels was found between the two groups. Hyporeninemic hypoaldosteronism was found in 3 patients with MMA who had different stages of kidney damage, and fludrocortisone was initiated, which normalized serum sodium and potassium levels.  Conclusions: This study, which has the largest number of patients among the studies investigating the renin-angiotensin system in organic acidemias to date, has demonstrated that hyporeninemic hypoaldosteronism is not a rare entity in the etiology of hyperkalemia in patients with MMA, and the use of fludrocortisone is an effective treatment of choice in selected cases. What is Known: • Hyperkalemia may be observed in cases of methylmalonic acidemia due to renal involvement and can be particularly prominent during metabolic decompensation. • Hyporeninemic hypoaldosteronism has been reported to be associated with hyperkalemia in only a few cases of methylmalonic acidemia. What is New: • Hyporeninemic hypoaldosteronism was found in one-fifth of cases with methylmalonic acidemia. • Fludrocortisone therapy leads to the normalization of serum sodium and potassium levels.

Prolonged postoperative hypoaldosteronism related to hyperkalemia in patients with aldosterone-producing adenoma.

Hyperkalemia is developed in a part of patients with aldosterone-producing adenoma (APA) after adrenalectomy, suspected to be due to the insufficiency of aldosterone secretion. The purpose of this study is to determine the frequency and characteristics of prolonged postoperative hypoaldosteronism (PPHA) using chemiluminescent enzyme immunoassay (CLEIA). We studied 58 patients with APA with long time after adrenalectomy and whose PAC was measured using a CLEIA kit. The PAC value measured using CLEIA was significantly lower than that of using RIA between two consecutive visits before and after the shift of measuring method of PAC (median [interquantile range], 123.0 [99.8-164.0] vs. 39.5 [15.8-64.2] pg/mL, p < 0.01). PAC was below the minimum limit of quantification (4.0 pg/mL) of the CLEIA kit at least once in nine patients (15.5%) who had PPHA. The PPHA group were older (mean ± standard deviation, 61.3 ± 8.5 vs. 50.5 ± 10.1 years, p < 0.01) and had lower eGFR (60.3 ± 14.0 vs. 82.3 ± 22.8 mL/min/1.73 m2, p < 0.01) than the non-PPHA group. The frequency of postoperative hyperkalemia (maximum serum potassium >5.5 mEq/L) was higher in the PPHA group than in the non-PPHA group (55.6% vs. 8.2%, p < 0.01). In conclusion, a few patients with APA long time after adrenalectomy had unmeasurable PAC using CLEIA. PPHA is likely to develop in patients with APA after adrenalectomy who are older and have impaired renal function. Additionally, PPHA is related to the occurrence of postoperative hyperkalemia.

Novel sonic hedgehog gene variant in a patient with hyponatremia, microsomia, and midline defects; phenotype description in association with a variant of unknown significance [c.755_757del p.(Phe252del)] and an approach to salt-wasting in SHH-related adrenal disorders.

OBJECTIVES: To contribute a novel sonic hedgehog (SHH) gene variant in association with a novel-meagerly described phenotype and discuss SHH signaling pathway pathology. CASE PRESENTATION: We present a 5-year-old boy with excessive hyponatremia and natriuresis, microform holoprosencephaly and microsomia, with morphologically intact hypothalamic-pituitary-adrenal (HPA) axis, and hypoaldosteronism, yet without hyperreninemia, hyperkalemia, dehydration episodes, or glucocorticoid insufficiency. Extensive workup excluded common causes of salt-wasting and revealed a novel variant of unknown significance on the sonic hedgehog (SHH) gene; NM_000193.4:c.755_757del (p.Phe252del), in heterozygosity. CONCLUSIONS: Salt-wasting in children is predominantly caused by central nervous system lesions, renal tubular dysfunction, or adrenal insufficiency. The SHH protein is a signaling molecule, essential in embryogenesis-including HPA axis differentiation. Inactivating SHH variants disrupt the signaling pathway, leading to dysplasia or dysfunction of target organs. What's new: • We analyze the patient's phenotype in the light of this novel variant • Patient's isolated aldosterone deficiency possibly implies a selective signaling defect affecting the development of adrenal zona glomerulosa • Unexplained hyporeninemia and hypokalemia in the context of hypoaldosteronism raise questions on SHH signaling pathophysiology.

Classification of pseudohypoaldosteronism type II as type IV renal tubular acidosis: results of a literature review.

Pseudohypoaldosteronism (PHA) type II (PHA2) is a genetic disorder that leads to volume overload and hyperkalemic metabolic acidosis. PHA2 and PHA type I (PHA1) have been considered to be genetic and pediatric counterparts to type IV renal tubular acidosis (RTA). Type IV RTA is frequently found in adults with chronic kidney disease and is characterized by hyperchloremic hyperkalemic acidosis with normal anion gap (AG). However, we recently observed that PHA1 was not always identical to type IV RTA. In this study, we focused on the acid-base balance in PHA2. Through a literature search published between 2008-2020, 46 molecularly diagnosed cases with PHA2 were identified (median age of 14 years). They comprised 11 sets of familial and 16 sporadic cases and the pathology was associated with mutations in WNK 4 (n = 1), KLHL3 (n = 17), and CUL3 (n = 9). The mean potassium (K+) level was 6.2 ± 0.9 mEq/L (n = 46, range 4.0-8.6 mEq/L), whereas that of chloride (Cl-) was 110 ± 3.5 mEq/L (n = 41, 100-119 mEq/L), with 28 of 41 cases identified as hyperchloremic. More than half of the cases (18/35) presented with metabolic acidosis. Although AG data was obtained only in 16 cases, all but one cases were within normal AG range. Both Cl- and HCO3- levels showed significant correlations with K+ levels, which suggested that the degree of hyperchloremia and acidosis reflect the clinical severity, and is closely related to the fundamental pathophysiology of PHA2. In conclusion, our study confirmed that PHA2 is compatible with type IV RTA based on laboratory findings.

ER ribosomal-binding protein 1 regulates blood pressure and potassium homeostasis by modulating intracellular renin trafficking.

BACKGROUND: Genome-wide association studies (GWASs) have linked RRBP1 (ribosomal-binding protein 1) genetic variants to atherosclerotic cardiovascular diseases and serum lipoprotein levels. However, how RRBP1 regulates blood pressure is unknown. METHODS: To identify genetic variants associated with blood pressure, we performed a genome-wide linkage analysis with regional fine mapping in the Stanford Asia-Pacific Program for Hypertension and Insulin Resistance (SAPPHIRe) cohort. We further investigated the role of the RRBP1 gene using a transgenic mouse model and a human cell model. RESULTS: In the SAPPHIRe cohort, we discovered that genetic variants of the RRBP1 gene were associated with blood pressure variation, which was confirmed by other GWASs for blood pressure. Rrbp1- knockout (KO) mice had lower blood pressure and were more likely to die suddenly from severe hyperkalemia caused by phenotypically hyporeninemic hypoaldosteronism than wild-type controls. The survival of Rrbp1-KO mice significantly decreased under high potassium intake due to lethal hyperkalemia-induced arrhythmia and persistent hypoaldosteronism, which could be rescued by fludrocortisone. An immunohistochemical study revealed renin accumulation in the juxtaglomerular cells of Rrbp1-KO mice. In the RRBP1-knockdown Calu-6 cells, a human renin-producing cell line, transmission electron and confocal microscopy revealed that renin was primarily retained in the endoplasmic reticulum and was unable to efficiently target the Golgi apparatus for secretion. CONCLUSIONS: RRBP1 deficiency in mice caused hyporeninemic hypoaldosteronism, resulting in lower blood pressure, severe hyperkalemia, and sudden cardiac death. In juxtaglomerular cells, deficiency of RRBP1 reduced renin intracellular trafficking from ER to Golgi apparatus. RRBP1 is a brand-new regulator of blood pressure and potassium homeostasis discovered in this study.

[Weigth Loss in a Neonate- A Case of Hypoaldosteronism].

The Neonatal weight loss is a common problem which most physicians who take care of newborns should recognise. The most common reason is insufficient dietary intake. However the reason can also be an underlying disease. Aldosterone insufficiency in neonates is a rare disease and if not treated correctly can be life threatening. It presents with serious electrolytes abnormalities and metabolic acidosis. It is therefore important to distinguish between serious and benign causes of weight loss in neonates.

Loss of LGR4/GPR48 causes severe neonatal salt wasting due to disrupted WNT signaling altering adrenal zonation.

Disorders of isolated mineralocorticoid deficiency, which cause potentially life-threatening salt-wasting crisis early in life, have been associated with gene variants of aldosterone biosynthesis or resistance; however, in some patients no such variants are found. WNT/ß-catenin signaling is crucial for differentiation and maintenance of the aldosterone-producing adrenal zona glomerulosa (zG). Herein, we describe a highly consanguineous family with multiple perinatal deaths and infants presenting at birth with failure to thrive, severe salt-wasting crises associated with isolated hypoaldosteronism, nail anomalies, short stature, and deafness. Whole exome sequencing revealed a homozygous splice variant in the R-SPONDIN receptor LGR4 gene (c.618-1G>C) regulating WNT signaling. The resulting transcripts affected protein function and stability and resulted in loss of Wnt/ß-catenin signaling in vitro. The impact of LGR4 inactivation was analyzed by adrenal cortex-specific ablation of Lgr4, using Lgr4fl/fl mice mated with Sf1:Cre mice. Inactivation of Lgr4 within the adrenal cortex in the mouse model caused decreased WNT signaling, aberrant zonation with deficient zG, and reduced aldosterone production. Thus, human LGR4 mutations establish a direct link between LGR4 inactivation and decreased canonical WNT signaling, which results in abnormal zG differentiation and endocrine function. Therefore, variants in WNT signaling and its regulators should systematically be considered in familial hyperreninemic hypoaldosteronism.

Clinical manifestations and associated factors in acquired hypoaldosteronism in endocrinological practice.

Introduction: Hypoaldosteronism can be congenital or acquired, isolated or part of primary adrenal insufficiency, and caused by an aldosterone deficit, resistance, or a combination of both. Reduced mineralocorticoid action can induce a decrease in urine K+ and H+ excretion and an increase in urine Na+ excretion, leading to hyperkalemia, and/or hyponatremia, often combined with metabolic acidosis. We aimed to characterize the clinical manifestations of hypoaldosteronism, and their associated factors. Methods: Retrospective analysis of 112 episodes of hypoaldosteronism diagnosed in 86 adult patients from 2012-2019 by the Endocrinology and Nutrition Department of a tertiary hospital. The frequency of hyperkalemia, hypovolemic hyponatremia (HH) and metabolic acidosis (MA), and their associated factors were evaluated. Results: Patients had a median age of 77 [65 - 84], 55.4% were male. 94.6% cases showed hyperkalemia, 54.5% HH, and 60.3% MA. The mean serum K+ of all cases was 5.4 ± 0.5 mmol/L, Na+: 132.1 ± 6.3 mmol/L, HCO3: 22.6 ± 3.3 mmol/L. Hypoaldosteronism was isolated in the majority of cases: only 6/112 (5%) had primary adrenal insufficiency. Hypovolemia was associated with hyponatremia and a more florid clinical presentation. HH was associated with a combined presence of aldosterone-lowering and mineralocorticoid resistance factors. MA was associated with the presence of mineralocorticoid resistance factors. Conclusions: Hypoaldosteronism in adult endocrinological clinical practice is primarily isolated, and acquired. It predisposes not only to the development of hyperkalemia and MA, but also to that of HH. Hypoaldosteronism must be considered in the differential diagnosis of HH with urinary sodium wasting.

Isolated hypoaldosteronism managed by DOCP in a dog with chronic kidney disease and hypercortisolism.

A 13-year-old spayed female Schnauzer dog with chronic kidney disease (CKD; International Renal Interest Society stage 2, non-proteinuric, normotensive), diabetes mellitus, hypercortisolism and myxomatous mitral valve degeneration (American College of Veterinary Internal Medicine stage B2) presented with electrolyte imbalance that had progressed to hyperkalaemia and hyponatremia, with a sodium to potassium (Na:K) ratio of 19.6. Cortisol levels after the adrenocorticotropic hormone stimulation test were within the therapeutic range, but aldosterone levels were below the reference range; hence, isolated hypoaldosteronism was diagnosed. After administration of deoxycorticosterone pivalate (DOCP), the electrolyte imbalance improved with a Na:K ratio of 27.7. This is the first report of the management of isolated hypoaldosteronism and hypercortisolism using trilostane and DOCP in a dog. This case highlights the importance of recognizing isolated hypoaldosteronism after long-term treatment with trilostane in a canine patient with CKD.

[Hyperkalemia due to low-molecular-weight heparin]. / Hyperkaliëmie bij laag-molecuulgewicht heparine.

BACKGROUND: The cause of hyperkalemia is frequently iatrogenic. Patient's prescriptions should therefore be checked in the analysis of the hyperkalemia. Low-molecular-weight heparin is not often suspected to cause this. CASE DESCRIPTION: A 64-year-old man, hospitalized because of a complicated clinical course of pancreatitis, developed an acute severe hyperkalemia. Further analysis was susceptive for hypoaldosteronism, which was confirmed with biochemical testing. The only drug that could cause hyperkalemia in this case was nadroparin, which was prescribed because of vena lienalis and a superior mesenteric vein thrombosis. A rechallenge with nadroparin showed a rapid rise in serum potassium, confirming our suspicion. CONCLUSION: In the diagnostic work-up of hyperkalemia, hypoaldosteronism should be considered in patients using LMWH. In particular when other risk factors for hyperkalemia are present, monitoring of potassium could be advised in patients receiving these agents.

Early Renin Recovery After Adrenalectomy in Aldosterone-Producing Adenomas: A Prospective Study.

The aim of the study was to clarify the relationship and the time of aldosterone and renin recoveries at immediate and long-term follow-up in aldosterone-producing adenoma (APA) patients who underwent adrenalectomy. Prospective and longitudinal protocol in a cohort of APA patients was followed in a single center. Among 43 patients with primary aldosteronism (PA), thirteen APA patients were enrolled in this study. Blood was collected for aldosterone, renin, potassium, creatinine, cortisol, and ACTH before and 1, 3, 5, 7, 15, 30, 60, 90, 120, 180, 270, 360 days after adrenalectomy. At diagnosis, most patients (84%) had hypokalemia and high median aldosterone levels (54.8; 24.0-103 ng/dl) that decreased to undetectable (<2.2) or very low (<3.0) levels between fifth to seventh days after surgery; then, between 3-12 months, its levels gradually increased to the lower normal range. The suppressed renin (2.3; 2.3-2.3 mU/l) became detectable between the fifteen and thirty days after surgery, remaining normal throughout the study. The aldosterone took longer than renin to recover (60 vs.15 days; p<0.002) and patients with higher aldosterone had later recovery (p=0.03). The cortisol/ACTH levels remained normal despite the presence of a post-operative hypoaldosteronism. Blood pressure and antihypertensive requirement decreased after adrenalectomy. In conclusion, our prospective study shows the borderline persistent post-operative hypoaldosteronism in the presence of early renin recovery indicating incapability of the zona glomerulosa of the remaining adrenal gland to produce aldosterone. These findings contribute to the comprehension of differences in renin and aldosterone regulation in APA patients, although both are part of the same interconnected system.

Pseudo-hypoaldosteronism secondary to infantile urinary tract infections: role of ultrasound.

BACKGROUND: The biochemical hallmarks of transient pseudo-hypoaldosteronism associated with a pyelonephritis include hyponatremia, hyperkalemia, and acidosis. We tested if the kidney-urinary tract ultrasound helps in predicting the diagnosis of overt pseudo-hypoaldosteronism in infants with a pyelonephritis. CASES PRESENTATION: Between 2013 and 2020, we managed 71 previously healthy infants 4 weeks to 24 months of age with a pyelonephritis (42 males and 29 females) and made the biochemical diagnosis of pseudo-hypoaldosteronism in 17 (24%). Infants with and without pseudo-hypoaldosteronism did not significantly differ with respect to the prevalence of kidney-urinary tract ultrasound abnormalities, graded by means of the UTD classification system of urinary tract abnormalities. CONCLUSIONS: Kidney-urinary tract ultrasound is almost routinely obtained in children with a febrile urinary tract infection. Our experience does not support the hypothesis that ultrasound might be relevant for the diagnosis of overt transient pseudo-hypoaldosteronism in babies affected by a urinary tract infection. Our data confirm the assumption that negative studies may be important for advancing clinical practice.

An unusual presentation of primary adrenal insufficiency with new onset type 1 diabetes: case report and review of the literature.

OBJECTIVES: To describe an atypical presentation of primary adrenal insufficiency in conjunction with new onset type 1 diabetes. CASE PRESENTATION: Here, we describe a case of new-onset type 1 diabetes (T1D) presenting simultaneously with an unusual presentation of primary adrenal insufficiency in a previously healthy 16-year-old. He was admitted for a typical presentation of diabetic ketoacidosis, but with extreme hyponatremia. An extensive workup revealed a low aldosterone level, appropriate cortisol level, and positive 21-hydroxylase antibodies. While the phenomenon of multiple autoimmune conditions developing in the same patient is well-described, this particular case has several atypical aspects. Our patient's case highlights the danger of relying on random serum cortisol in the setting of acute illness to rule out adrenal insufficiency. CONCLUSIONS: Adrenal insufficiency can present as isolated hypoaldosteronism without hypocortisolemia and can manifest as severe hyponatremia in the context of diabetic ketoacidosis. Workup for an unusual presentation of T1D should include a 21-hydroxylase antibody, as well as thyroid and celiac disease studies.

Catch-up Growth and Discontinuation of Fludrocortisone Treatment in Aldosterone Synthase Deficiency.

BACKGROUND: Aldosterone synthase deficiency (ASD) caused by mutations in the CYP11B2 gene is characterized by isolated mineralocorticoid deficiency. Data are scarce regarding clinical and biochemical outcomes of the disease in the follow-up. OBJECTIVE: Assessment of the growth and steroid profiles of patients with ASD at the time of diagnosis and after discontinuation of treatment. DESIGN AND METHOD: Children with clinical diagnosis of ASD were included in a multicenter study. Growth and treatment characteristics were recorded. Plasma adrenal steroids were measured using liquid chromatography-mass spectrometry. Genetic diagnosis was confirmed by CYP11B2 gene sequencing and in silico analyses. RESULTS: Sixteen patients from 12 families were included (8 females; median age at presentation: 3.1 months, range: 0.4 to 8.1). The most common symptom was poor weight gain (56.3%). Median age of onset of fludrocortisone treatment was 3.6 months (range: 0.9 to 8.3). Catch-up growth was achieved at median 2 months (range: 0.5 to 14.5) after treatment. Fludrocortisone could be stopped in 5 patients at a median age of 6.0 years (range: 2.2 to 7.6). Plasma steroid profiles revealed reduced aldosterone synthase activity both at diagnosis and after discontinuation of treatment compared to age-matched controls. We identified 6 novel (p.Y195H, c.1200 + 1G > A, p.F130L, p.E198del, c.1122-18G > A, p.I339_E343del) and 4 previously described CYP11B2 variants. The most common variant (40%) was p.T185I. CONCLUSIONS: Fludrocortisone treatment is associated with a rapid catch-up growth and control of electrolyte imbalances in ASD. Decreased mineralocorticoid requirement over time can be explained by the development of physiological adaptation mechanisms rather than improved aldosterone synthase activity. As complete biochemical remission cannot be achieved, a long-term surveillance of these patients is required.

Impaired aldosterone response to ACTH without hypoaldosteronism: An unrecognized secretory pattern in search of clinical implications.

CONTEXT: Aldosterone has been recently characterized as a 'stress hormone'. Stress per se elicits a sizable rise in aldosterone secretion, which could be replicated by the administration of a low dose (0.03-1 µg, IV) of adrenocorticotropic hormone (ACTH). Whether or not the aldosterone response to ACTH could be selectively impaired, that is, in association with intact cortisol response, is presently unknown. OBJECTIVE: To determine whether or not the aldosterone response to low dose of ACTH is impaired in subjects referred to assess the hypothalamic-pituitary-adrenal axis (HPA). DESIGN: Retrospective analysis. SETTING: Outpatient referral endocrine day care centre. PATIENTS: One hundred and ninety-five consecutive subjects who underwent the low dose (1 µg) ACTH test, in whom decreased cortisol reserve was suspected due to former/present glucocorticoid excess, pituitary disease or/and unexplained weakness. MAIN OUTCOME MEASURES: The outcome was the detection of lack of aldosterone response, defined as a rise <111 pmol/l. RESULTS: In all, 46/195 subjects had subnormal aldosterone response as compared with 52/195 subjects showing diminished cortisol response. Nine subjects had combined deficient aldosterone and cortisol response. In the 37 subjects with isolated subnormal aldosterone response common associations were the use of exogenous glucocorticoids, mostly prednisone (n = 16); former Cushing disease (n = 2); nonfunctioning pituitary adenoma (n = 8); hypothyroidism (n = 11); the use of statins (n = 11), angiotensin-converting enzyme inhibitors or angiotensin receptor blockers (n = 6), sex steroids in transgenders and orthostatic hypotension (n = 3). Twenty-seven percent (25/93) of the subjects with recent exposure to glucocorticoids had impaired aldosterone response to ACTH. CONCLUSION: Blunted aldosterone response to ACTH in the absence of hypoaldosteronism was seen in ~27% of subjects referred for HPA assessment using the low dose 1 µg ACTH test. Exposure to glucocorticoid excess was often linked to this impairment, independent of the cortisol response to ACTH.

Cotrimoxazole-induced hyperkalaemia in a patient with known hypoaldosteronism.

A70-year-old man, with established hypoadrenalism due to a previous bilateral adrenalectomy, was admitted with recurrent episodes of postural dizziness and presyncope. He had been discharged from hospital 3 weeks earlier on a 1-month course of cotrimoxazole following a diagnosis of prostatitis. His electrolytes on admission showed new onset hyponatraemia and hyperkalaemia.His usual glucocorticoid replacement dose was doubled in view of a presumed diagnosis of hypocortisolaemia. However, the hyperkalaemia persisted. On rereviewing his treatment, we suspected a possible diagnosis of cotrimoxazole-induced hyperkalaemia. Cotrimoxazole was stopped and ciprofloxacin started instead. His fludrocortisone replacement was doubled for 3 days after stopping treatment to decrease his postural symptoms. His postural symptoms improved, his serum potassium decreased to normal levels and he was safely discharged.It is essential to remember that cotrimoxazole, a commonly used antibiotic, can induce a potentially fatal hyperkalaemia especially in patients with known hypoadrenalism.