Final answer:
In patients with a glomerular filtration rate (eGFR) below 20 mL/min, loop diuretics such as furosemide (Lasix) are the preferred choice over thiazide diuretics.
Step-by-step explanation:
In patients with a glomerular filtration rate (eGFR) below 20 mL/min, thiazide diuretics are generally not effective due to their mechanism of action in the distal convoluted tubule of the nephron. Thiazide diuretics inhibit the reabsorption of sodium and chloride in this part of the nephron.
However, loop diuretics such as furosemide (Lasix) are effective in patients with reduced kidney function (eGFR below 20 mL/min). These medications work by inhibiting the reabsorption of sodium and chloride in the loop of Henle, which is located before the distal convoluted tubule.
Therefore, in patients with an eGFR below 20 mL/min, loop diuretics are the preferred choice over thiazide diuretics.