Chronically elevated levels of pro-inflammatory cytokines: Interleukin (IL)- 2 &6, C-Reactive Protein (CRP), tissue necrosis factor-alpha (TNF-alpha) is a feature common to both OSA and anemia of chronic illness (AI). Because intermittent hypoxia, the presumed stimulus for proinflammatory mediator release, may also stimulate erythropoietin, the development of anemia may be obscured. Hepcidin, a hepatically produced polypeptide is greatly upregulated in the presence of IL-6 but not IL-2. Hepcidin, possibly interacting with increased levels of IL-6, may contribute to AI. We sought to determine the effects of OSA on hepcidin levels.
Prospectively, 10 patients with severe OSA were enrolled if they lacked any other explainable etiology of chronic inflammation and they provided their written consent. For each, demographics, medical history, physical findings were determined, overnight polysomnography (PSG) performed, and venous blood collected to measure hepcidin, hemoglobin(Hb)/hematocrit(Hct), iron/total iron binding capacity (TIBC), erythropoietin levels, kidney and liver function. Blood was collected at 8 pm the evening before the study of the PSG. Hepcidin was measured by mass spectrometry. Data are presented as mean with standard deviation (st dev.) values.
5 females and 5 males 52 (st dev 15) years were studied. No woman was menstruating. For the entire study cohort, BMI = 35.5 (st dev 6), Epworth Score = 13, apnea hypopnea index (AHI) = 48 events/hour (st dev 24), awake room air pulse oxyhemoglobin saturation (PSAO2) = 97% (st dev 3), hypoxic time (total sleep time with PSAO2 < 90%) = 59 minutes (st dev 24), Hb/Hct = 13.5 g/dl/40 % (st dev 1.2/3.6 resp.), iron = 70mcg/dl (st dev 27), TIBC = 336 mcg/dl (st dev 58), erythropoietin 16.6 (st dev 9), hepcidin = 3.04 (st dev 2.1) and 3.9 (st dev 3.5) nM women/men respectively.
In our group of patients with severe OSA, anemia was not seen however hepcidin levels were normal.
General applicability of these results to those with OSA, however, requires larger studies in order to establish roles of anemia and hepcidin.
Amir Khan, No Financial Disclosure Information; No Product/Research Disclosure Information