What is the primary effect of Fanconi's syndrome?

The primary effect of Fanconi's syndrome is indeed impaired renal tubular function. This condition is characterized by a dysfunctional proximal tubule, which is responsible for the reabsorption of various substances such as glucose, amino acids, bicarbonate, phosphate, and uric acid. As a result, these substances leak into the urine and are lost from the body, leading to metabolic disturbances.

In Fanconi's syndrome, the tubular cells are unable to adequately perform their reabsorption duties, leading to generalized renal tubular acidosis and the excretion of significant amounts of important nutrients and electrolytes. This impairment highlights the specific problem of tubular function over glomerular filtration damage or other renal issues associated with the other choices.

Conditions like diabetic nephropathy or protein loss due to infections involve different mechanisms of renal impairment that do not primarily stem from the dysfunction of renal tubules, further emphasizing why impaired tubular function is the hallmark effect of Fanconi's syndrome.