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Understanding the process of successful adaptation to high altitude provides valuable insight into the pathogenesis of conditions associated with impaired oxygen uptake and utilization. Prepubertal children residing at low altitude show a reduced cerebrovascular response to exercise in comparison to adults, and a transient uncoupling of cerebral blood flow to changes in the partial pressure of end-tidal CO

Developmental cerebral hemodynamic adaptations to chronic high-altitude exposure, such as in the Sherpa population, are largely unknown. To examine hemodynamic adaptations in the developing human brain, we assessed common carotid (CCA), internal carotid (ICA), and vertebral artery (VA) flow and middle cerebral artery (MCA) velocity in 25 (9.6 ± 1.0 yr old, 129 ± 9 cm, 27 ± 8 kg, 14 girls) Sherpa children (3,800 m, Nepal) and 25 (9.9 ± 0.7 yr old, 143 ± 7 cm, 34 ± 6 kg, 14 girls) age-matched sea level children (344 m, Canada) during supine rest. Resting gas exchange, blood pressure, oxygen saturation and heart rate were assessed. Despite comparable age, height and weight were lower (both P < 0.01) in Sherpa compared with sea level children. Mean arterial pressure, heart rate, and ventilation were similar, whereas oxygen saturation (95 ± 2 vs. 99 ± 1%, P < 0.01) and end-tidal Pco2 (24 ± 3 vs. 36 ± 3 Torr, P < 0.01) were lower in Sherpa children. Global cerebral blood flow was ∼30% lower in Sherpa compared with sea level children. This was reflected in a lower ICA flow (283 ± 108 vs. 333 ± 56 ml/min, P = 0.05), VA flow (78 ± 26 vs. 118 ± 35 ml/min, P < 0.05), and MCA velocity (72 ± 14 vs. 88 ± 14 cm/s, P < 0.01). CCA flow was similar between Sherpa and sea level children (425 ± 92 vs. 441 ± 81 ml/min, P = 0.52). Scaling flow and oxygen uptake for differences in vessel diameter and body size, respectively, led to the same findings. A lower cerebral blood flow in Sherpa children may reflect specific cerebral hemodynamic adaptations to chronic hypoxia. NEW & NOTEWORTHY Cerebral blood flow is lower in Sherpa children compared with children residing at sea level; this may reflect a cerebral hemodynamic pattern, potentially due to adaptation to a hypoxic environment.

ObjectiveTo assess the iodine status of Sherpa residents living in Kunde village, Khumbu region, Nepal.DesignPrevalence of goitre was determined by palpation. Urinary iodine concentrations (UIC) were determined in casual morning samples, and thyroid-stimulating hormone (TSH) in finger-prick blood samples on filter paper. Dietary and demographic data were obtained via questionnaire, and selected foods analysed for iodine.SettingKhumbu region is an area of low soil iodine in Nepal, where the prevalence of goitre was greater than 90 % in the 1960s prior to iodine intervention.SubjectsTwo hundred and fifteen of 219 permanent residents of Kunde were studied.ResultsOverall prevalence of goitre was 31 % (Grade 1 goitre, 27·0 %; Grade 2, 4·2 %). When adjusted to a world population, goitre prevalence was 27 % (95 % CI 23, 32 %); Grade 2 goitre prevalence was 2·8 % (95 % CI 1·0, 4·6 %). Median UIC was 97 μg/l, but only 75 μg/l in women of childbearing age. Thirty per cent had UIC < 50 μg/l and 52 % had UIC < 100 μg/l, while 31 % of children aged 300 μg/l. Ten per cent of participants had TSH concentrations >5 μU/ml.ConclusionsThe prevalence of severe iodine deficiency has decreased since the 1960s, but mild iodine deficiency persists, particularly in women of childbearing age. The consumption of high-iodine uncooked instant noodles and flavour sachets by school-aged children contributed to their low prevalence of goitre and excessive UIC values. This finding may obscure a more severe iodine deficiency in the population, while increasing the risk of iodine-induced hyperthyroidism in children. Ongoing monitoring is essential.

The purpose of this study was to examine ventricular structure and function in Sherpa adolescents to determine whether age-specific differences in oxygen saturation (SpO2) and pulmonary artery systolic pressure (PASP) influence cardiac adaptation to chronic hypoxia early in life. Two-dimensional, Doppler, and speckle-tracking echocardiography were performed on adolescent (9–16 yr) highland Sherpa (HLS; 3,840 m; n = 26) and compared with age-matched lowland Sherpa (LLS; 1,400 m; n = 10) and lowland Caucasian controls (LLC; sea level; n = 30). The HLS were subdivided into pre- and postadolescence; SpO2 was also recorded. Only HLS exhibited a smaller relative left ventricular (LV) end-diastolic volume; however, both HLS and LLS demonstrated a lower peak LV untwisting velocity compared with LLC (92 ± 26 and 100 ± 45 vs. 130 ± 43°/s, P < 0.05). Although SpO2 was similar between groups, PASP was higher in post- vs. preadolescent HLS (30 ± 5 vs. 25 ± 5 mmHg, P < 0.05), which negatively correlated with right ventricular strain rate ( r = 0.50, P < 0.01). Much like their adult counterparts, HLS and LLS adolescents exhibit slower LV diastolic relaxation, despite residing at different altitudes. These findings suggest fundamental differences exist in the diastolic function of Sherpa that are present at an early age and may be retained after migration to lower altitudes. The higher PASP in postadolescent Sherpa is in contrast to previous reports of lowland children at high altitude and, unlike that in lowlanders, was not explained by differences in SpO2; thus different regulatory mechanisms seem to exist between these two distinct populations.

To determine the prevalence of Helicobacter pylori (H. pylori) among Sherpa residents of the Upper Khumbu region of Nepal and to test for associations between presence of H. pylori infection and lifestyle and health measures.Written questionnaires were used to collect data from 383 individuals in randomly selected households in three villages of the region. Early morning stool samples were tested immediately for the presence of H. pylori antigen using standard rapid diagnostic Pylori strips. A descriptive data analysis was performed to estimate overall prevalence and its association with age, sex, dyspepsia, smoking, alcohol intake, diet, and medication use.The overall prevalence of H. pylori in the study sample was 70.5%. The prevalence was high in all the three villages of Thame, Kunde and Fortse. Prevalence was high in all age groups, including a high prevalence of 78.1% in children aged10 years. The presence of H. pylori was not significantly associated with any of the lifestyle and health measures collected, including dyspeptic symptoms, medication, smoking, alcohol intake and dietary factors like salt, smoked food, fruit/vegetable and pickle consumption.The overall prevalence of H. pylori in Upper Khumbu is high with the infection being acquired early in the first decade of life. This lifelong infection may explain the very high incidence of gastric cancer in this community. The rate of infection is not dependent on individual variables including demographic, social and dietary factors.