The evaluation of Large Language Models (LLMs) in medicine has predominantly relied on English-language benchmarks aligned with North American clinical guidelines, limiting their applicability to other healthcare systems. In this paper, we evaluate twenty-two proprietary and open-weight LLMs on the 2025 National Examination for the Evaluation of Medical Training (ENAMED), a high-stakes, government-standardized assessment used to evaluate medical graduates in Brazil. The benchmark comprises 90 multiple-choice questions grounded in Brazilian public health policy, clinical practice, and Portuguese medical terminology, and is released as an open dataset. Model performance is measured using both standard accuracy and the official Item Response Theory (IRT) framework employed by ENAMED, enabling direct comparison with human proficiency thresholds. Results reveal a clear stratification of model capabilities: proprietary frontier models achieve the highest performance, whereas many open-weight and smaller-domain-adapted models fail to meet the minimum proficiency criterion. Across comparable scales, large generalist models consistently outperform specialized medical fine-tunes, suggesting that general reasoning capacity is a stronger predictor of success than narrow domain adaptation in this setting. These findings establish ENAMED as a rigorous benchmark for evaluating medical LLMs in Portuguese and highlight both the potential and current limitations of such models for educational assessment.

Retrieval-Augmented Generation (RAG) is proposed to reduce hallucination and improve grounding in clinical language models, yet its effectiveness across different levels of clinical reasoning remains unclear. We conducted a controlled evaluation of medication-related question answering in Portuguese using over 7,000 Brazilian regulatory drug leaflets and a complementary clinical benchmark derived from national medical licensing examinations (Revalida and Fuvest). Retrieval substantially improved factual recall and clinical coherence in medication-specific queries, increasing F1 from 0.276 to 0.412. However, naive retrieval did not consistently improve complex clinical reasoning and sometimes reduced accuracy compared to a parametric-only baseline. We identify retrieval-induced anchoring bias, where partially relevant evidence shifts model decisions toward clinically incorrect conclusions. Critique-based and adaptive retrieval mitigated this effect and achieved the highest clinical benchmark accuracy (54.25%). Clinically grounded evaluation dimensions revealed safety-relevant differences beyond traditional NLP metrics. These results show that retrieval augmentation is effective in regulatory settings but requires adaptive control for higher-level clinical reasoning.

The lack of high-quality test collections challenges Information Retrieval (IR) in specialized domains. This work addresses this issue by comparing supervised classifiers against zero-shot Large Language Models (LLMs) for automated relevance annotation in the oil and gas industry, using human expert judgments as a benchmark. A supervised classifier, trained on limited expert data, outperforms LLMs, achieving an F1-score that surpasses even a second human annotator. The study also empirically confirms that LLMs are susceptible to unfairly prefer technologically similar retrieval systems. While LLMs lack precision in this context, a well-engineered classifier offers an accurate and practical path to scaling evaluation datasets within a human-in-the-loop framework that empowers, not replaces, human expertise.