Hyporeninemic Hypoaldosteronism Treatment & Management

If the patient has severe hyperkalemia or electrocardiographic (ECG) abnormalities are present, emergency measures for hyperkalemia are necessary (see Hyperkalemia). The need for dialysis in patients with hyperkalemia and mild chronic kidney disease (CKD) is uncommon, because medical measures usually suffice.

Drug therapy for hyperkalemia may itself have adverse effects; in particular, patients must be adequately monitored for overtreatment with resulting hypokalemia, congestive heart failure (CHF), or metabolic alkalosis (depending on the agent[s] used).

Because many clinically important classes of medications have a tendency to produce a picture reflecting renal tubular acidosis (RTA) type IV, preventing this condition by eliminating the patient’s use of those agents is impossible. Rather, enable early detection by conducting laboratory screenings of patients at risk, after starting medicines in those classes.

Failure to adhere to monitoring guidelines after starting medications that have a risk of exacerbating RTA type IV is a pitfall, because although hyperkalemia is treatable, it may be lethal if undetected.

If the patient presents with hyperkalemia as a complication of urinary tract obstruction, institute appropriate urologic measures.

Reduce or, if at all possible, eliminate medications that cause or may exacerbate potassium retention. The long-term approach is to utilize measures that increase net potassium excretion by the renal or intestinal routes.

Diuretics

Loop and thiazide diuretics are well known for their ability to promote kaliuresis and chloruresis. Although these effects are usually viewed as adverse ones, in RTA type IV they are exploited as a way of removing potassium and treating the acidosis.

Diuretics are the first-line therapy for patients with signs of volume overload on examination. Caution these patients to ignore the label that pharmacists may put on the diuretic bottle instructing them to take the diuretic with a glass of orange juice. The main adverse effects of diuretics are overdiuresis with volume depletion and alkalosis.

Sodium bicarbonate

Sodium bicarbonate (ie, NaHCO₃) is administered in 10-grain (650-mg) tablets. This adjunctive agent usually corrects the acidosis and, by increasing distal delivery of bicarbonate anion, increases urinary potassium excretion. NaHCO₃ tablets may be used as a first-line agent in patients with more severe acidosis (eg, 14-16 mEq/L) or in volume-depleted patients who should not be given diuretics. Consumption of NaHCO₃ may cause the patient to belch and may also lead to volume overload.

Fludrocortisone

Fludrocortisone is the third-line agent for patients with RTA type IV. This synthetic corticosteroid is unique in that its mineralocorticoid activity significantly exceeds its glucocorticoid activity.

Fludrocortisone is used as an aldosterone analogue; however, the dosage needed to achieve effective kaliuresis is generally 0.1-0.3 mg/day, which is higher than the dosage used as replacement in patients with adrenal insufficiency. This underscores the importance of tubular hyporesponsiveness to aldosterone in most patients with RTA type IV.

Fludrocortisone can exacerbate hypertension and fluid overload, and patients taking this drug need close follow-up care. It should also be kept in mind that fludrocortisone has some glucocorticoid activity, with the resultant metabolic and long-term side effects.

Reports regarding the adverse effects of endogenous aldosterone on cardiac remodeling in patients with CHF raise serious concerns about the long-term use of fludrocortisone, suggesting that it should be avoided unless all other methods are exhausted.

Sodium polystyrene sulfonate

Sodium polystyrene sulfonate is an exchange resin that is useful in achieving potassium removal via the colon, thereby bypassing the impaired renal excretory mechanisms. It now is available in premixed doses in a sorbitol solution (to provide the necessary laxation ).

Sodium polystyrene sulfonate is of variable effectiveness in this setting; however, on average, it removes 1 mEq of potassium for each 1 g ingested, at the cost of about 1 mEq of absorbed sodium. This sodium retention may be problematic for patients with CHF or impaired renal function.

Compliance is an issue for long-term use because sodium polystyrene sulfonate is not very palatable. If the patient develops constipation, this agent is ineffective. Intestinal complications of oral or rectal use are well known.

Sodium polystyrene sulfonate clearly has a role in the long-term treatment of patients for whom other kaliuretic approaches have failed, patients who are intolerant to these approaches, or patients who are noncompliant with dietary restrictions. It cannot be used in patients with ileostomy (absence of colon), ileus, or obstruction or in patients who have recently undergone intestinal surgery.

Consult a dietitian for assistance in teaching the patient about a potassium-restricted diet. Consultation with a urologist will be necessary if urinary tract obstruction is discovered. Because many cardiac medications (eg, angiotensin-converting enzyme [ACE] inhibitors, angiotensin receptor blockers [ARBs], beta blockers, and aldosterone inhibitors) produce hyperkalemia, a cardiologic consultation may be indicated to design a cardiac regimen that is compatible with the patient’s intolerance of these medication classes.

Recommend a dietary review, preferably by a renal dietitian, to uncover sources of dietary potassium excess. Salt substitutes commonly are overlooked, which often contain large amounts of potassium chloride (KCl). Dietary teaching also is an important part of long-term therapy.

• Advise a 2-g potassium restriction, including complete avoidance of KCl-containing salt substitutes

• Address sodium intake – Sodium intake is variable because most patients are hypertensive or retain salt as a result of CKD, but some patients waste salt

• Counsel patients against the use of over-the-counter (OTC) nonsteroidal agents

• Caution patients on the use of herbal remedies and dietary supplements unless these are known to be safe

Although there are no published data regarding whether to impose activity restrictions on patients with RTA type IV, there is a theoretical concern that these patients might be ill equipped to handle the transient hyperkalemia that strenuous exercise produces. Accordingly, instruct patients to approach strenuous exercise with caution and to proceed with it only if stable control of potassium is demonstrated.

Before discharge, ensure that the patient’s potassium level has stabilized within an acceptable range on a regimen suitable for outpatient use. Generally, a stable potassium level below 5.5 mEq/L is acceptable, provided that the patient is compliant with diet, medications, and follow-up care. For those patients who may be less compliant, tighter control may be targeted to provide some margin of safety.

Ensure that the patient received dietary counseling. Educate patients about the risk of sudden catastrophic events from hyperkalemia and the importance of compliance with medications, diet, and follow-up procedures. Schedule timely outpatient follow-up care and laboratory testing.

Outpatient care consists of monitoring the response to therapy, with particular attention paid to blood pressure, volume status, and electrolytes.

If RTA type IV was exacerbated by a drug that was discontinued, further therapy directed toward lowering potassium may no longer be needed and may even cause harm by giving rise to hypokalemia and alkalosis.