High-Dose vs Standard Ergocalciferol for Vitamin D Normalization in Aggressive Non-Hodgkin Lymphoma

The goal of this clinical trial is to evaluate whether a high-intensity loading dose of ergocalciferol (vitamin D2) can normalize blood vitamin D levels more rapidly and safely than standard weekly dosing in patients with newly diagnosed aggressive non-Hodgkin lymphoma. The study will also assess the safety of both dosing strategies. The main questions it aims to answer are: * Does a high-intensity loading dose of ergocalciferol lead to faster normalization of serum 25-hydroxyvitamin D levels compared with standard weekly dosing? * Are there differences in safety and adverse events between the two dosing strategies? Researchers will compare a high-intensity loading dose regimen of ergocalciferol with a standard weekly dosing regimen to determine differences in vitamin D normalization and safety outcomes. Participants will: * Be randomly assigned to receive either a high-intensity loading dose or a standard weekly dose of ergocalciferol (vitamin D2) * Receive standard first-line immunochemotherapy for aggressive non-Hodgkin lymphoma * Have blood tests to monitor vitamin D levels, calcium, phosphate, and safety parameters at scheduled visits * Be followed for treatment response, survival outcomes, and adverse events during and after therapy