Husain Yahya Alkhaldy

Background/Objectives: The kinetics of blood volume and hemoglobin mass (Hbmass) adaptation in newcomers to moderate altitude and the time required to reach the hematological phenotype of long-term residents remain poorly defined. We aimed to characterize this trajectory over six months and to compare newcomers with established altitude residents. Methods: Thirty-seven healthy male sea-level newcomers were prospectively followed at baseline (within 48 h of arrival), two months, and six months after relocation to Abha, Saudi Arabia (2250 m). Hbmass, blood volume (BV), plasma volume (PV), and red blood cell volume (RBCV) were measured by CO rebreathing; lean body mass (LBM) was assessed by DXA. Six-month values were compared with 107 long-term male altitude residents. Linear mixed-effects models with Holm–Bonferroni correction were used. Results: Adaptation followed a biphasic trajectory. At two months, RBCV and Hbmass rose significantly from baseline (RBCV + 186 mL, Hbmass + 65 g; both p ≤ 0.005), confirmed by LBM-adjusted analysis. These gains partially regressed by six months, after which no volume parameter differed significantly from baseline. Hemoglobin (Hb) and hematocrit (Hct) remained persistently elevated (+6 g/L, +1.9%; both p < 0.001) due to sustained PV contraction. Compared with long-term residents, six-month newcomers had significantly lower LBM-adjusted Hbmass (15.7 vs. 18.0 g/kg), RBCV (48.0 vs. 54.2 mL/kg), and BV (98.9 vs. 109.8 mL/kg; all p < 0.001), yet Hb and Hct were not significantly different. Conclusions: Moderate altitude acclimatization follows a transient two-month erythropoietic increase, then partial regression. Six months is insufficient to attain the oxygen-carrying capacity of long-term residents’ deficit entirely masked by Hb and Hct. Direct Hbmass measurement normalized to LBM is required for accurate assessment of altitude adaptation.

Background: Residing at high altitude is associated with increased red blood cell volume (RBCV) and reduced plasma volume (PV), changes that complicate interpretation of hemoglobin (Hb) and hematocrit (Hct). Here, we assess blood volume (BV), RBCV, PV, and hemoglobin mass (Hbmass) in individuals living at moderate altitude with the aim of deriving reference range for use in clinical practice. Methods: One hundred and fifty-eight moderate-altitude residents (ALT; 51 women) from Abha, Saudi Arabia (2250 m above sea level) were recruited and compared to 40 control subjects (CON; 0 women). Blood volumes and Hbmass were determined by carbon monoxide rebreathing. Lean body mass (LBM) was quantified by dual-energy X-ray absorptiometry and adjusted for. Results: When normalized to LBM, ALT men displayed an 8% increase in BV (109 vs 101 mL, p = 0.003), 14.8% increase in RBCV (54 vs 47 mL, p < 0.001), and 16.2% increase in Hbmass (18 vs 15 g, p < 0.001) compared to CON. ALT women exhibited lower BV (3928 vs 5476 mL), RBCV (1684 vs 2690 mL), PV (2276 vs 2767 mL), and Hbmass (558 vs 886 g), than ALT men, (p < 0.001 for all). When expressed per body weight, ALT men have higher RBCV (33 vs 30 g), lower PV (34 vs 40 mL) and no different BV (68 vs 69 mL, p = 0.443). When expressed per LBM, gender differences in RBCV and Hbmass disappeared (RBCV: 54 vs 51 mL/kg^LBM, p = 0.164; Hbmass: 18 vs 17 g/kg^LBM, p = 0.201). Women have significantly higher BV (120 vs 109 mL/kg^LBM) owing to higher PV (72 vs 55 mL/kg^LBM). Conclusion: Moderate altitude is associated with a higher BV owing to a higher RBCV, which also explains the elevated Hb. A reference range based on the 5% and 97.5% percentiles of blood volumes and Hbmass adjusted for LBM is suggested for use in clinical practice.

At high altitudes, increased red blood cell volume (RBCV) and reduced plasma volume (PV) complicate interpretation of hemoglobin (Hb) and hematocrit (HCT) values. Whether moderate altitude affects these parameters remains debated. This study aimed to assess hemoglobin mass (Hb mass) and intravascular volumes at moderate altitude. Participants were recruited from a moderate-altitude population (2250 m above sea level) in the Aseer region, Saudi Arabia. Eligible individuals were healthy, with no medical conditions or prescribed medications. Participants with baseline Hb and HCT values outside the reference range were excluded. Hb mass, blood volume (BV), RBCV, and plasma volume (PV) were measured using the carbon monoxide (CO) rebreathing method. Body composition was assessed using dual-energy X-ray absorptiometry (DEXA). Results were reported as absolute values and normalized to body weight (BW) and lean body mass (LBM). Ninety-four participants (30 females, 64 males; mean age 25.8 ± 10.6 years) were included. Males had significantly higher absolute Hb mass (922.8 ± 195.0 vs 594.9 ± 91.2 g, P < .001), BV (5625.0 ± 1209.0 vs 4231.0 ± 881.0 mL, P < .001), PV (2903.0 ± 717.0 vs 2480.0 ± 552.0 mL, P = .005), and RBCV (2721.2 ± 56.9 vs 1749.8 ± 37.8 mL, P < .0001), as well as higher normalized Hb mass^(BW) (11.7 ± 3.1 vs 9.9 ± 2.4 g/kg^BW, P = .007) and RBCV^BW (34.6 ± 8.8 vs 29.2 ± 7.1 mL/kg, P = .004). No gender differences were found in BV (P = .658) or PV (P = .155) when normalized to BW. Differences in Hb mass (P = .37) and RBCV (P = .39) also disappeared when normalized to LBM. However, females had higher BV^{L BM} (126.8 ± 23.7 vs 110.9 ± 15.3 mL/kg^LBM, P = .007) and PV^LBM (75.0 ± 14.2 vs 56.6 ± 8.2 mL/kgLBM, P < .001). Compared to historical sea-level controls, altitude participants showed higher absolute Hb mass in males (P = .01) and females (P = .014), with higher values per LBM (P < .0001 for both). Hb and HCT showed significant but weak correlations with Hb mass and intravascular volumes. Residents at moderate altitudes have elevated Hb mass compared to sea-level references using the CO rebreathing technique. Population- and altitude-specific reference ranges for blood volumes and Hb mass CO rebreathing technique are needed for clinical application.

Introduction: Thrombosis stands as a significant contributor to both morbidity and mortality in individuals afflicted with myeloproliferative neoplasms. This retrospective study investigated the association between JAK2 mutations and venous thrombosis at unusual sites, and in young individuals with ischemic stroke, residing at high altitudes in the Aseer region, Saudi Arabia. Patients and Methods: Data were collected from two high-altitude referral hospitals over three years (2020– 2022). Records of all JAK2 mutation tests were reviewed. Those requested as part of evaluation of thrombosis events, without known myeloproliferative neoplasms (MPNs) were analysed. Results: Among the 208 JAK2 tests, 40 (19.2%) were linked to thrombotic event evaluations. The cohort, with a median age of 41, included 17 (42.7%) males and 23 females, with 57.5% having completely normal complete blood counts (CBC). Thrombotic events were divided between splanchnic vein thrombosis (36.6%) and cerebral thrombosis (34.1%), while the remaining cases involved unprovoked deep vein thromboses/pulmonary embolisms and portal vein thrombosis. Only 2 (5%) participants tested positive for JAK2 mutations: a 17-year-old male diagnosed concurrently with polycythemia vera after renal vein thrombosis and a 31-year-old woman with hepatic vein thrombosis and a normal CBC. Conclusion: This study reveals that JAK2 mutations are infrequently found in high-altitude patients with unprovoked DVT, PE, or atypical thrombosis. While JAK2 testing is notably relevant for splanchnic vein thrombosis, its routine use for other thrombotic events, particularly with normal CBC results, remains uncertain. Given the study’s limitations, further prospective research with larger cohorts is needed to refine guidelines for JAK2 mutation testing in various thrombotic contexts.

Background: Social history taking is an important element of a medical interview. No previous studies, however, addressed public attitudes regarding social history taking in Saudi Arabia. Objective: This study explores public attitudes about the importance of social history taking by doctors in Southern Saudi Arabia. Methods: A cross-sectional study was conducted to collect public opinion about social history taking using a self-administered questionnaire. Social history taking was defined as questions about general sociodemographics (job, income, marital status, housing conditions, and animal contact) and social habits (travel, smoking, alcohol drinking, illicit drug use, and sexual history). Descriptive statistics were conducted, along with a comparison between categorical variables. Results: A total of 510 respondents completed the questionnaire, of which 381 (74.7%) had a medical history taken before. A complete social taking was not obtained from those with medical history previously taken. Marital status (73.2%), smoking (49.1%), and occupation (32.8%) were the commonest inquiries, while income (3.7%) and sexual history (6.6%) were the least. Most respondents had no reservations about answering questions about their social history. Among the general demographic questions, job and marital status were more likely to be answered, whereas income and housing inquiries were less likely to be answered. Among social habits, sexual history followed by illicit drug use and alcohol drinking inquiries were less likely to be answered. Conclusion: Detailed social history taking is uncommon among doctors. The public is open to discussing their social status and habits. However, questions involving income, housing, and some social habits like illicit drugs, alcohol, and sexual history are less likely to be faithfully reported and thus need to be handled appropriately. It is crucial for healthcare providers to approach social history taking with sensitivity and respect and to create a private environment for patients where they can freely and accurately share their social histories.

Purpose: Complete blood count (CBC) is a commonly used blood test for health checks. This study was conducted to compare CBC from two different altitudes and from sea-level populations in order to suggest correction factor for altitude-related increment on the hemoglobin and red blood cell indices. Patients and Methods: In this retrospective lab records study, large datasets of CBCs over 5-year period were screened from three different regions of Saudi Arabia, Jeddah (a coastal city), Taif City located at 1879 m above sea level, and Abha City at located 2270 m above sea level. Descriptive analysis and significance testing of the CBC variables at different altitude were compared. Results: A total of 57,059 participants were included for final analysis. Mean hemoglobin (Hb) concentration (g/dL) was 14.81 for men and 13.77 for women at sea level, whereas Hb concentrations were 15.35 and 14.19 for men and women residing at Taif City, respectively, and 15.40 and 14.71 for men and women at Abha City, respectively. Hemoglobin and other red cell indices were significantly different among men and women across different altitude, except for mean corpuscular volume (MCV). The MCV 95^th percentile range was lower at sea level and both altitudes as compared to current reference range (76– 91 fL vs 81– 98 fL). Conclusion: Although altitude-associated increment in Hb concentration was evident in both men and women, it was lower than as suggested by World Health Organization and Centers for Disease and Control. Results of this study can also be used to derive new CBC reference intervals for Saudi residents living at high altitude. A correction factor (ΔHb) of 0.30 g/dL per 1000 m altitude is suggested to be used in adult population living at high altitudes in Saudi Arabia which should help better define anemia and polycythemia at altitude.

Objective: Isolated mild neutropenia is a common clinical problem in some ethnicities including Arabs and Middle Eastern population. The current study aims to authenticate the prevalence of isolated neutropenia in Southern and Southwestern Saudi Arabia, explore the effect of altitude or regional differences and to suggest a new reference range for neutrophil count. Methods: In this retrospective cross-sectional study, laboratory results of a commercial laboratory were screened over a period of 5 years (2016– 2020) in seven different cities of different altitudes in South and southwestern Saudi Arabia. Participants’ laboratory investigations were reviewed and excluded for any abnormal complete blood count, renal profile, liver profile, lipid profile, thyroid function test, fasting blood glucose, or HbA1c findings. Descriptive analysis and 95th percentile range were calculated using standard statistical methods. Results: A total of 91,880 complete blood count results were included in the final analysis. Isolated neutropenia was common laboratory finding, with a prevalence ranging from 11% to 23%. The 2.5th percentile of the neutrophil count was lower than currently utilized 1.5× 10⁹/L in all studied seven cities. Conclusion: Mild to moderate neutropenia is common in Southern and Southwestern Saudi Arabia. Benign ethnic neutropenia (BEN) likely explains this high prevalence. Since BEN has no clinical significance, the reference range for normal neutrophil counts needs to be adjusted to reflect the effect of BEN.

Objectives: Isolated mild neutropenia is a common clinical problem. The current study aims to validate our previous findings regarding the high prevalence of isolated neutropenia in Southern and Southwestern Saudi Arabia and explore the effect of altitude or regional differences. Methods: In this retrospective cross-sectional study, laboratory results of a commercial laboratory were screened over a period of 5 years (2016–2020) in seven different cities in South and southwestern Saudi Arabia. Participants’ laboratory investigations were reviewed and excluded for any ab-normal complete blood count, renal profile, liver profile, lipid profile, thyroid function test, fasting blood glucose, or HbA1c findings. Descriptive analysis and 95th percentile range were calculated using standard statistical methods. Results: A total of 91,880 complete blood count results were included in the final analysis. isolated neutropenia is common laboratory finding, with a prevalence ranging from 11-23%. The 2.5th percentile of the neutrophil count was lower than 1.5×109/L in all seven cities. Conclusions: Mild to moderate neutropenia is common in Southern and Southwestern Saudi Arabia. Benign ethnic neutropenia (BEN) may explain this high prevalence. Since BEN has no clinical significance, the reference range for normal neutrophil counts needs to be adjusted to reflect the effect of BEN.

Introduction: Isolated neutropenia is a common problem in hematology practice. Benign ethnic neutropenia (BEN) is the common form of neutropenia worldwide and it affects mainly African and Middle Eastern ethnicities. Most cases of isolated mild and moderate neutropenia are benign and associated with no clinical significance. The aim of this study was to estimate the prevalence of isolated neutropenia at high-altitude southern Saudi Arabia. Methods: A large dataset of complete blood counts (CBCs) was analyzed for walk-in patients of both genders, of age ranges from 12 to 60 years doing blood tests at a commercial lab for high altitude − 2,270 meters above sea level – (HA) group, and from sea level SL group. Abnormal biochemical or CBC results were excluded before analysis. Results: For HA group, 3123 CBCs were analyzed and for SL group 18,427 CBCs were analyzed. The prevalence of mild neutropenia, defined as absolute neutrophil count (ANC) in the range of 1.0− .5× 10⁹/L, was 12.4% (n=399) versus 5.6% (n=1025), while moderate neutropenia, defined as ANC of 0.5– 1 × 10⁹/L, was present 6% (n=191) versus 1.45% (n=269) in the high altitude and sea level groups, respectively. Severe neutropenia, defined as neutrophil count less than 0.5– 1 × 10⁹/L, was rare in both groups. Conclusion: Isolated neutropenia is common in Saudis living at high altitude. While benign ethnic neutropenia (BEN) is thought to be the major contributing factor to this high prevalence, other factors including environmental factors and altitude are possible contributing factors along with underlying ethnic neutropenia.

Introduction: The prevalence of iron deficiency, latent and symptomatic, is heterogeneous worldwide. In this study, we aim to explore the prevalence of iron deficiency, with and without anemia, among medical college females at the high Altitude Aseer region of Southwestern Saudi Arabia. Methodology: 200 female medical students were randomly sampled, between the ages of 19 and 27 years. Blood samples were collected for complete blood count (CBC) values and serum ferritin determination. Questionnaires were completed in order to collect demographics, medical history, and socioeconomic information of the participants. Results: Prevalence of overall iron deficiency was high (63%, serum ferritin <20 μg/L, 52.5%, ferritin <15 μg/L). Anemia, adjusted for high altitude (defined as less than 13 g/dL was present in 41 participants (20.5%) and 12 (6.5%) have Hb <12 g/dL. Iron-deficiency anemia (Hb <13 g/dL and serum ferritin <15 μg/L) was present in 35 (17.5%). Personal and family history of anemia and poor animal product containing meals were positively correlated with the presence of iron deficiency state. Neither symptoms of anemia, nor the presence of menorrhagia correlate with the presence of iron deficiency anemia. Conclusion: Iron deficiency with and without anemia is a very common and condition in young females’ population at high altitude. Implementing a lab method to screen for anemia on vulnerable populations is needed. Frequently asymptomatic, the primary care providers should maintain a high degree of suspicion in order to initiate screening for iron status.