Conn syndrome was named after J. W. Conn who first described it in 1955, in a patient who had hypertension with an aldosterone-producing adenoma. The adenoma is characterized by increased aldosterone secretion from the adrenal glands, suppressed plasma renin, hypertension, and hypokalemia. Later, many other cases of adrenal hyperplasia with inappropriately elevated aldosterone secretion were described, and now the term primary hyperaldosteronism is used to describe Conn syndrome irrespective of whether the patient has an adenoma or not.[1][2]
The diagnosis of Conn syndrome is not always easy but recognition is important as this condition can help cure hypertension with surgical or medical management. However, it is important to distinguish aldosteronoma from idiopathic adrenal hyperplasia. Aldosteronomas are removed surgically, whereas idiopathic adrenal hyperplasia is managed with medications. At the same time, one as to be aware that there are conditions that cause elevated aldosterone levels including familial disease, aldosterone-producing renin-responsive adenomas. ectopic secretion (from kidneys and ovary) and adrenocortical carcinomas.
The syndrome may be secondary to adrenal hyperplasia, adrenal adenoma, aldosterone-secreting adrenal carcinoma (1%), or familial hyperaldosteronism (FH).[3][4][5]
Various specific genetic alterations (see below) have been identified for rare familial forms of the disease. In a majority of these genetic alterations, the endpoint is Ca influx and membrane depolarization resulting in aldosterone hypersecretion.
Mutations in three other genes encoding for membrane proteins (Na/K-ATPase (ATP1A), ca ATPase (ATP2B3) and Ca1.3 (CACNAID) are associated with Ca influx and/or activated calcium signaling pathways leading to increased production of aldosterone by CYP11B2 gene.
Recently, a single-nucleotide polymorphism (c.-2G>C) of the NR3C2 gene that codes for mineralocorticoid receptor (MR) has been shown to be associated with increased activation of RAS and increased blood pressure in the general population.
In most cases, the aldosteronomas arise from the zona fasciculata. There is often significant glandular hyperplasia.
Primary hyperaldosteronism is the most common cause of secondary hypertension and occurs in about 6% to 20% of adult hypertensive patients, higher in patients with resistant hypertension. The prevalence of 10% was noted when consecutive patients with hypertension were evaluated. However, the prevalence increased to 30% when aldosterone to renin ratio (ARR) was used as a screening method in general practice.
Aldosterone-producing adenoma is present in 50% to 60%, and the remaining is idiopathic or bilateral adrenal hyperplasia. It is about two times more common in women than in men.
Primary hyperaldosteronism is caused by aldosterone-producing adenomas, bilateral idiopathic adrenal hyperplasia, aldosterone-producing adrenal carcinoma, and familial aldosteronism. The increased amount of aldosterone potentiates renal sodium reabsorption and water retention, and potassium excretion. The increased sodium reabsorption by the kidneys results in plasma volume expansion which is the primary initiating mechanism for hypertension. This may induce tissue inflammation and heightened sympathetic drive, with subsequent development of fibrosis in vital organs, such as heart, kidneys, and vasculature. As a result, this may lead to the development of chronic kidney disease, atrial fibrillation, stroke, ischemic heart disease, and congestive heart failure.[6][7]
Besides the elevation in sodium, patients often develop hypokalemia and metabolic alkalosis. Nearly 1/5th of patients with Conn syndrome have impairment in glucose tolerance which is due to the inhibitory effects of hypokalemia on insulin secretion
Histopathology is often heterogeneous ranging from micronodular or macronodular hyperplasia with adenoma formation, with atrophy or diffuse or nodular hyperplasia of the adjacent adrenal cortex.
Often, the patients are asymptomatic but may present with symptoms of fatigue, muscle weakness, cramping (secondary to potassium wasting), headaches, and palpitations. They can also have polydipsia and polyuria from hypokalemia-induced nephrogenic diabetes insipidus.
Many patients are discovered to have Conn syndrome as a result of persisting hypokalemia and hypertension. Others may present with serious arrhythmias after being started on diuretics for hypertension. Finally, there are some patients who present with hypertension that is refractory to treatment.
Physical findings:
It is important to note that Conn syndrome is not associated with edema because of spontaneous natriuresis.
Hypokalemia in a hypertensive patient is the most common clue for primary hyperaldosteronism. However, normal serum potassium may be present in up to 38% of patients, especially in patients with adrenal hyperplasia or familial aldosteronism.[8][9]
Blood work will reveal hypokalemia, hypernatremia and metabolic alkalosis due to the actions of aldosterone on the distal convoluted tubule.
Prior to measuring aldosterone levels it is important to know the diurnal rhythm of the hormone. The lowest levels of aldosterone are observed around midnight and the highest values are seen in the morning between 7-8 am. This diurnal rhythm is preserved in patients with Conn syndrome but rare in idiopathic adrenal hyperplasia.
When to screen?
The goals of treatment include normalizing blood pressure, electrolytes and aldosterone levels. The treatment depends on the cause
Unilateral adrenalectomy in patients with a unilateral adenoma (Conn syndrome) cures hypertension in 30% to 60% of cases, but the mean cure rate is only 19% after unilateral or bilateral adrenalectomy in patients with idiopathic hyperaldosteronism whose treatment mainly is medical. This treatment includes aldosterone antagonists such as spironolactone or eplerenone or other potassium-sparing diuretics like amiloride.
To decrease risks of elevated blood pressure during surgery, patients need to be optimized preoperatively. Aldosterone antagonists like eplerenone and spironolactone are associated with survival benefits.
To lower blood pressure, spironolactone is preferred as it also normalizes serum potassium levels and plasma volume. In a small group of patients with glucocorticoid-mediated hyperaldosteronism, low doses of corticosteroids can help with blood pressure control.
Nonsurgical treatment is an option for patients who are frail and have numerous comorbidities. In addition, bilateral adrenal hyperplasia is also managed medically.
Adrenalectomy is used to excise unilateral lesions. Prior to surgery, the patient has to be treated with spironolactone for 4-6 weeks. Today, laparoscopic adrenalectomy is widely used to excise the adrenal gland.
Results
About 2/3rd of patients become normotensive after surgery but the blood pressure may take 6-12 months to stabilize. Over 5 years, only about 50% of patients will remain normotensive. Those who fail to respond to spironolactone prior to surgery will most likely continue to be hypertensive after surgery.
Conn syndrome is associated with high morbidity and mortality if it is left untreated. The primary cause of the morbidity is linked to hypertension and hypokalemia, the latter is known to cause cardiac arrhythmias that can be fatal.
Complications are often related to the underlying chronic hypertension that can cause acute myocardial infarction, stroke and heart failure. Most important, hypertension can also lead to retinopathy and end-stage renal disease. The surgery for Conn syndrome can also lead to complications.
After surgery, the blood pressure has to be monitored for many months. Some patients may develop significant hyperkalemia that may require treatment with diuretics.
A low salt diet is recommended especially since it helps in the management of hypertension.
The diagnosis and management of Conn syndrome is best done with an interprofessional team. The disorder can be difficult to diagnose because of the lack of standardized tests. In addition, the ARR may be falsely elevated in patients with chronic kidney disease, patients on potassium supplements or beta-blockers. Diuretics, angiotensin-converting enzyme inhibitors, and angiotensin receptor blockers may cause false-negative results. If the clinical suspicion is high, ARR should be repeated after holding these agents for two weeks.
Unilateral adrenalectomy in patients with a unilateral adenoma (Conn syndrome) cures hypertension in 30% to 60% of cases, but the mean cure rate is only 19% after unilateral or bilateral adrenalectomy in patients with idiopathic hyperaldosteronism whose treatment mainly is medical. This treatment includes aldosterone antagonists such as spironolactone or eplerenone or other potassium-sparing diuretics like amiloride.
Due to the challenges of managing this disease, the pharmacist should be involved in diuretic selection and dosing. The pharmacist should check for drug-drug interaction and report back to the clinical interprofessional team concerns. The nurses monitoring the patient should be familiar with the pathophysiology and expected abnormalities in laboratory testing. Due to the precarious challenges of abnormal potassium, the nurse should be prepared to report to the clinical team quickly any untoward abnormalities as daily lab screens are reported. Only through interprofessional team involvement and close monitoring can the best results be achieved. [Level 5][10]
[1] | Deinum J,Groenewoud H,Wilt GJV,Rossi G,Lenzini L, Adrenal venous sampling: cosyntropin stimulation or not? European journal of endocrinology. 2019 Jun 1; [PubMed PMID: 31176302] |
[2] | Cobb A,Aeddula NR, Primary Hyperaldosteronism 2019 Jan; [PubMed PMID: 30969601] |
[3] | Corssmit EPM,Dekkers OM, Screening in adrenal tumors. Current opinion in oncology. 2019 May; [PubMed PMID: 30844886] |
[4] | Stowasser M,Wolley M,Wu A,Gordon RD,Schewe J,Stölting G,Scholl UI, Pathogenesis of Familial Hyperaldosteronism Type II: New Concepts Involving Anion Channels. Current hypertension reports. 2019 Apr 4; [PubMed PMID: 30949771] |
[5] | Chikladze NM,Favorova OO,Chazova IE, Family hyperaldosteronism type I: a clinical case and review of literature. Terapevticheskii arkhiv. 2018 Sep 20; [PubMed PMID: 30701745] |
[6] | Morera J,Reznik Y, MANAGEMENT OF ENDOCRINE DISEASE: The role of confirmatory tests in the diagnosis of primary aldosteronism. European journal of endocrinology. 2019 Feb 1; [PubMed PMID: 30475220] |
[7] | Infante M,Armani A,Marzolla V,Fabbri A,Caprio M, Adipocyte Mineralocorticoid Receptor. Vitamins and hormones. 2019; [PubMed PMID: 30678856] |
[8] | Chan PL,Tan FHS, Renin dependent hypertension caused by accessory renal arteries. Clinical hypertension. 2018; [PubMed PMID: 30410790] |
[9] | Schilbach K,Junnila RK,Bidlingmaier M, Aldosterone to Renin Ratio as Screening Tool in Primary Aldosteronism. Experimental and clinical endocrinology [PubMed PMID: 30165708] |
[10] | Sernyak MJ, Implementation of monitoring and management guidelines for second-generation antipsychotics. The Journal of clinical psychiatry. 2007 [PubMed PMID: 17539695] |