Blood viscosity in clinical practice: A critical review of diagnostic utility, therapeutic implications, and evidence gaps.

Blood viscosity is a key rheological measure that is a biomarker of hematological, cardiovascular, and inflammatory conditions. This systematic review analyzed the changing role of blood viscosity and its potential significance in clinical practice. We provide a comprehensive examination of diagnostic methods, ranging from gold-standard rotatory viscometers to novel point-of-care and microfluidic technologies, emphasizing the practical features for precise data interpretation. This comprehensive clinical study revealed unique hemorheological profiles of different clinical conditions and diseases, particularly emphasizing the genetic constitution of sickle cell disease, diabetes mellitus with vascular consequences, and other diseases and syndromes associated with hyperviscosity. We provide a new approach for assessing the clinical value of viscosity as a pathophysiological description, prognostic biomarker, and decision-making measure. The review emphasizes that although substantial evidence supports its prognostic significance, many deficiencies remain in the research results relating to viscosity-guided therapies to improve patient care outcomes. The integration of artificial intelligence, wearable monitoring, and customized hemorheology was analyzed with caution. This synthesis emphasizes the need for established methods, interdisciplinary cooperation, and focused clinical trials to convert blood rheological knowledge into clinical applications for precise blood and cardiovascular therapies.