Oxygen saturation, measured by pulse oximetry (SpO), is a vital clinical measure. Our descriptive, cross-sectional study describes SpO measurements from 6289 healthy subjects from age 1 to 80 years at 15 locations from sea level up to the highest permanent human habitation. Oxygen saturation measurements are illustrated as percentiles. As altitude increased, SpO decreased, especially at altitudes above 2500 m. The increase in altitude had a significant impact on SpO measurements for all age groups. Our data provide a reference range for expected SpO measurements in people from 1 to 80 years from sea level to the highest city in the world.

Insulinoma is a rare pancreatic neuroendocrine tumor that is usually described as benign, sporadic, and very small (<2 cm). However, there have been rare case reports of insulinoma presenting as a giant tumor. We describe 3 cases of giant insulinomas, all of which developed liver metastases. The patients were aged 38, 63, and 67 years. Clinically, all patients presented with Whipple's triad associated with a large mass located in the pancreatic tail. The tumors ranged in size from 10 to 15 cm. On microscopic examination, the tumors were well differentiated with amyloid deposition ranging between 20% and 30%. Immunohistochemically, all 3 tumors showed strong diffuse expression of chromogranin and synaptophysin, whereas they were only focally positive for insulin. One patient developed liver recurrence 3 years after resection of the primary tumor yet remained asymptomatic without treatment. Another patient with liver recurrence underwent right hepatectomy and has been free of disease for 2 years. The third patient died of metastatic disease 13 years after initial surgery. Giant insulinomas are characterized by focal expression of insulin and high rates of liver metastases. Long-term follow-up is mandatory in these patients, as recurrence is expected after primary surgery.

Chronic mountain sickness (CMS) results from chronic hypoxia. It is unclear why certain highlanders develop CMS. We hypothesized that modest increases in fetal hemoglobin (HbF) are associated with lower CMS severity. In this cross-sectional study, we found that HbF levels were normal (median = 0.4%) in all 153 adult Andean natives in Cerro de Pasco, Peru. Compared with healthy adults, the borderline elevated hemoglobin group frequently had symptoms (headaches, tinnitus, cyanosis, dilatation of veins) of CMS. Although the mean hemoglobin level differed between the healthy (17.1 g/dL) and CMS (22.3 g/dL) groups, mean plasma erythropoietin (EPO) levels were similar (healthy, 17.7 mIU/mL; CMS, 12.02 mIU/mL). Sanger sequencing determined that single-nucleotide polymorphisms in endothelial PAS domain 1 (EPAS1) and egl nine homolog 1 (EGLN1), associated with lower hemoglobin in Tibetans, were not identified in Andeans. Sanger sequencing of sentrin-specific protease 1 (SENP1) and acidic nuclear phosphoprotein 32 family, member D (ANP32D), in healthy and CMS individuals revealed that non-G/G genotypes were associated with higher CMS scores. No JAK2 V617F mutation was detected in CMS individuals. Thus, HbF and other classic erythropoietic parameters did not differ between healthy and CMS individuals. However, the non-G/G genotypes of SENP1 appeared to differentiate individuals with CMS from healthy Andean highlanders.

No abstract

Background In Latin America, the prevalence of end-stage kidney disease (ESKD) has risen tremendously during the last decade. Previous studies have suggested that receiving dialysis at high altitude confers mortality benefits; however, this effect has not been demonstrated at &gt;2000 m above sea level (masl) or in developing countries. Methods This historical cohort study analyzed medical records from six Peruvian hemodialysis (HD) centers located at altitudes ranging from 44 to 3827 masl. Adult ESKD patients who started maintenance HD between 2000 and 2010 were included. Patients were classified into two strata based on the elevation above sea level of their city of residence: low altitude (&lt;2000 masl) and high altitude (≥2000 masl). Death from any cause was collected from national registries and Cox proportional hazards models were built. Results A total of 720 patients were enrolled and 163 (22.6%) resided at high altitude. The low-altitude group was significantly younger, more likely to have diabetes or glomerulonephritis as the cause of ESKD and higher hemoglobin. The all-cause mortality rate was 84.3 per 1000 person-years. In the unadjusted Cox model, no mortality difference was found between the high- and low-altitude groups {hazard ratio [HR] 1.20 [95% confidence interval (CI) 0.89–1.62]}. After multivariable adjustment, receiving HD at high altitude was not significantly associated with higher mortality, but those with diabetes as the cause of ESKD had significantly higher mortality [HR 2.50 (95% CI 1.36–4.59)]. Conclusions In Peru, patients receiving HD at high altitudes do not have mortality benefits.