Iron Deficiency in Pulmonary Hypertension—Prevalence, Impact on Prognosis and Disease Burden in Pulmonary Arterial Hypertension and Pulmonary Hypertension Related to Hypoxia: A Review

Pulmonary hypertension (PH) is recognized for being a severe, chronic phenomenon that necessitates a careful multidisciplinary approach. Its frequent coexistence with multiple comorbidities highlights the need for tailored decision-making concerning treatment towards not only certain PH subtypes but also towards each individual patient as well. Pulmonary arterial hypertension (PAH) management has undergone extensive development, which enabled patients' life expectancy to be prolonged. The targeted treatment made a significant contribution to the improvement of the patients' quality of life, thereby reducing the illness burden. However, apart from the administration of drugs in the course of PAH, there is also the field for determining and addressing modifiable factors, which may influence everyday life and the final outcome of these individuals. Taking into consideration the fact that iron deficiency (ID) is the most prevalent nutritional deficit worldwide and that there exists a well-established, scientifically supported correlation between ID and the outcome and prognosis of left heart failure patients, multiple studies were conducted in order to verify a possible connection between ID and right heart failure as well. Indeed, the crossroads of iron and PAH, PH related to hypoxia, and pathophysiological mechanisms linking pulmonary vasculature and ID have been eagerly investigated over recent years. Therefore, research provided a considerable amount of data in this area, emphasizing the potential usefulness of iron homeostasis to serve as a prognostic factor. Nevertheless, due to extensive exploration of this matter, several issues have arisen that demand further study and clarification, with the use of a proper ID definition being one of the most crucial. Herein, we present a concise review of the most up-to-date literature regarding iron's homeostasis and pulmonary vascular bed through the prism of PAH and PH related to hypoxia.