Sunday, January 4, 2015

Primary Hyperaldosteronism

An issue that commonly arises in both the outpatient and inpatient settings is the combination of hypertension and hypokalemia. When should these patients be worked up for primary hyperaldosteronism? How do you work these patients up? Let's discuss the diagnosis and management

  • Primary aldosteronism commonly presents with hypertension and hypokalemia. However, normokalemia is present 50% of patients.
  • The most common causes of primary aldosteronism are aldosterone-producing adenomas (APAs) and bilateral adrenal hyperplasia.
  • Abnormally high release of aldosterone leads to an increased risk of cardiovascular disease and morbidity, including left ventricular hypertrophy, myocardial infarction and stroke.
  • 2008 Endocrine Society Guidelines, test for primary aldosteronism in patients with:
    • Hypertension and hypokalemia (diuretic induced-hypokalemia less than 3 or spontaneous hypokalemia less than 3.5.
    • Severe or resistant hypertension
    • Hypertension and an adrenal incidentaloma
    • Hypertension and a family history of early-onset hypertension or CVA age before the age of 40.
    • Hypertension and first-degree relatives with documented primary aldosteronism
  • The initial evaluation:
    • Measure plasma renin activity (PRA) or plasma renin concentration (PRC) and plasma aldosterone concentration.
    • In primary hyperaldosteronism, PRA and PRC are reduced and the plasma aldosterone concentration (PAC) is inappropriately high (approximately PAC/PRA greater than 20 (550 in SI units).
  • This ratio is not sufficient for a diagnosis. You then need suppression testing.
  • This can be performed with orally administered sodium chloride and measurement of urinary aldosterone excretion. Alternatively, it can be done with IV sodium chloride loading and measurement of the PAC. 

  • Once Primary Hyperaldosteronism is confirmed, adrenal CT is done to distinguish between aldosterone-secreting adenoma and bilateral hyperplasia. Adrenal CT will also help to asses for adrenocortical carcinoma.
  • When the CT scan is normal, shows bilateral abnormalities, or shows a unilateral abnormality but the patient is over age 35 years, adrenal venous sampling is recommended to confirm unilateral disease if the patient would like to pursue surgical management of their primary aldosteronism. 
  • The reason 35 years is a significant cut-off is because patients above this age are more likely to have non-functioning adenomas, so you may not be certain that the detected mass accounts for the elevated hyperaldosteronism.