A 5-year old child of severe nephrotic syndrome on treatment with tacrolimus, frusemide and prednisolone developed seizures. The investigations revealed: Serum Na+ = 136 mEq/L Blood urea = 78 mg/dL Serum creatinine = 0.5 mg/dL Serum albumin = 1.5 g/dL Serum total Ca = 7.5 mg/dL Urine albumin = 2g What is the likely cause of symptoms in this baby?

**Core Concept**
The underlying principle being tested involves the **pathophysiology of nephrotic syndrome** and its treatment, particularly the side effects of **immunosuppressive** and **diuretic** medications. Nephrotic syndrome is characterized by severe proteinuria, hypoalbuminemia, and edema.

**Why the Correct Answer is Right**
Given the child is on **tacrolimus**, **frusemide**, and **prednisolone**, and developed seizures, the likely cause is related to these medications. **Tacrolimus** is known for its **neurotoxicity**, which can manifest as seizures, especially in the context of altered renal function affecting its clearance. **Frusemide** can cause **hypokalemia** and **hyponatremia**, but the serum sodium level is within normal limits. **Prednisolone** is less likely to cause seizures directly.

**Why Each Wrong Option is Incorrect**
**Option A:** This choice is not provided, but typically, other options might include electrolyte imbalances or other medication side effects.
**Option B:** Without the specific option, it's challenging to address, but if it involved another medication or condition not supported by the information given, it would be incorrect.
**Option C:** Similarly, without specifics, if this option suggested a condition unrelated to the medications or the patient's presentation, it would not be the correct answer.
**Option D:** Again, lacking the specific details of this option, if it did not align with the patient's symptoms and medication profile, particularly the known side effects of tacrolimus, it would be incorrect.

**Clinical Pearl / High-Yield Fact**
It's crucial to remember that **tacrolimus** has a narrow therapeutic index and can cause **neurotoxicity**, including seizures, especially in patients with renal dysfunction affecting drug clearance. Monitoring of drug levels is essential to prevent such complications.

**Correct Answer:** D. Tacrolimus toxicity.

✓ Correct Answer: B. Tacrolimus toxicity