6 Complications of Renal Dysfunction Practice Questions

How kidney dysfunction causes complications

Kidney dysfunction can impair regulation of water, sodium, potassium, acid, phosphate, calcium, and vitamin D. It can also contribute to anemia and symptoms associated with waste buildup. These complications may require clinical evaluation; learning about them does not replace clinical assessment.

Fluid and sodium balance

When kidney excretion of sodium and water is impaired, both can be retained and extracellular fluid can expand. This can contribute to edema, rising blood pressure, and pulmonary congestion, such as crackles heard at the lung bases. These findings are consistent with Fluid overload.

Edema together with a low measured serum sodium does not necessarily mean that total-body sodium is low. Excess water relative to sodium can lower the measured serum sodium concentration, so the result must be interpreted alongside fluid status and clinical context.

Potassium and cardiac effects

Reduced kidney capacity to excrete potassium can lead to Hyperkalemia. A classic electrocardiogram finding associated with hyperkalemia is peaked T waves. High potassium can disrupt cardiac electrical activity and may cause dangerous arrhythmias; suspected severe elevation or concerning symptoms require urgent medical assessment.

Acid–base changes

Chronic kidney disease can contribute to Metabolic acidosis through reduced kidney acid excretion and bicarbonate production. In the example with arterial pH $7.29$, bicarbonate $16\ \mathrm{mmol/L}$, and arterial carbon dioxide pressure $\mathrm{PaCO_2}=32\ \mathrm{mm\ Hg}$, the low pH indicates acidemia and the low bicarbonate points to a primary metabolic process. The reduced $\mathrm{PaCO_2}$ is consistent with respiratory compensation.

Mineral, vitamin D, and bone changes

As chronic kidney disease advances, impaired phosphate handling and reduced activation of vitamin D contribute to a characteristic pattern: phosphate increases, calcitriol decreases, and parathyroid hormone (PTH) increases. These changes contribute to secondary hyperparathyroidism and CKD–mineral and bone disorder.

Anemia in kidney disease

Advanced chronic kidney disease can cause normocytic anemia in part because damaged kidneys may produce less Erythropoietin, the hormone that signals bone marrow to make red blood cells. Iron deficiency and other causes should also be considered when evaluating anemia.

Waste buildup and symptoms

In advanced kidney failure, waste products and fluid can build up. Uremic complications may include nausea, reduced appetite, itching, fatigue, and confusion or difficulty concentrating.

Putting the complication patterns together

The major complication patterns connect impaired kidney functions to clinical findings: sodium and water retention can contribute to edema, hypertension, and pulmonary congestion; impaired potassium excretion can lead to hyperkalemia; and reduced acid excretion and bicarbonate production can contribute to metabolic acidosis. Advancing chronic kidney disease can also disrupt phosphate and vitamin D regulation, contribute to anemia, and produce symptoms associated with waste buildup.