Evaluación de parámetros clínicos y de laboratorio relacionados con el diagnóstico de insulino resistencia / Evaluation of clinical and laboratory parameters related to the diagnosis of insulin resistance

The evaluation of insulin resistance (IR) in clinical practice is based on the determination of fasting insulin (I0) and insulin level after 2 hours in an oral glucose tolerance test (OGT). However, there are not adequate cutoff points to discriminate IR patients. Objectives: to evaluate the reliability of insulin levels in the diagnosis of IR using the intravenous insulin tolerance test (IVITT) as the gold standard. Patients and Method: The OGT and IVITT of patients who participated as cases or controls in research protocols were analyzed. We excluded those cases with fasting glycemia over126 mg/dl. Results: 128 cases, 111 F, 17 M; Age: 40.3 +/- 14.8 years; BMI: 33 +/- 8 kg/m2; Waist circumference, M: 100.3 +/- 9.4 cm, F: 96 +/- 15 cm. According to IVITT (KITT), 103 (80.5 percent) were IR (KITT < 4.5 percent) and 25 (19.5 percent) were non IR (KITT > 4.5 percent). Fasting (G0) and 120 minutes after glucose challenge glycemia (G120), I0 and I120, HOMA and area under the glycemia and insulin curve, were significantly higher in the IR, as the same as, hypertension and acanthosis nigricans features (p < 0.05). According to G120, 45 cases (35.2 percent) had glucose intolerance, 9 (7 percent) diabetes and 74 (57.8 percent) were normals. In addition to G0, only IVITT was significantly different among the 3 groups (p = 0.025), identifying most insulin resistant subjects. The sensitivity and specificity for a cutoff point of I120 at 60 µIU/mL, were 30 percent and 88 percent, respectively. Conclusion: Baseline and 120 minutes post glucose charge insulin levels and HOMA, do not discriminate insulin resistant subjects, especially when there is fasting or post-stimulus hyperglycemia. Therefore, they are not recommended for individual diagnosis or therapeutic decisions

Determinación de niveles de vitamina D en pacientes con fibromialgia: estudio de casos y controles / Vitamin D levels in patients with fibromyalgia: case control study

Introduction: fibromyalgia (FM) is characterized by diffuse chronic muscle pain, fatigue and disability, affecting quality of life. In recent years there are many reports that show a high prevalence of vitamin D deficiency in different populations. In patients with FM there are conflicting results about the associations with vitamin D deficiency. Method: Case control study matched controls by age and sex. A clinical interview, measurement of 25-OH vitamin D, calcium, phosphorus and intact PTH was measured. The definitions of the American Society of Endocrinology were used: Insufficient vitamin D levels of 21-29 ng/ml and deficiency when they are less than 20 ng/ml. Results: 39 female patients were included in each group. The average age was 46.33 years (SD 10.6) in patients with FM and 45.92 years (SD 11.9) in controls. VD average levels in women with FM was 26.13 ng/ml (SD 8.3) and the controls of 28.45 ng/ml (SD 8.7) p = 0.082. No group differences were found when using cutoffs of 30 ng/dl (OR 2.75 with p = 0.35 [95 percent CI 0.96 to 8.06]) or 20 ng/dl (OR 0,6 p = 0.38 [95 percent CI 0.15 to 2.18]). No VD patients with levels below 10 ng/dl were presented. Conclusions: We found no differences between groups in VD levels when considering the average levels of VD or using different cutoffs.

Síndrome de hipoglicemia autoinmune: Primeros casos en Chile / Insulin autoimmune syndrome: Report of two cases

Insulin autoimmune syndrome (IAS) is characterized by spontaneous hypoglycemia with extremely high insulin levels and the presence of circulating autoantibodies against insulin, in patients who have never been exposed to exogenous insulin. We report two patients with the syndrome. A 36 years old male presenting with hypoglycemia in the emergency room had an oral glucose tolerance test showed basal and 120 min glucose levels of 88 and 185 mg/dl. The basal and 120 min insulin levels were 2,759 and 5,942 μUI/ml. The presence of an insulin secreting tumor was discarded. Anti-insulin antibodies were positive. He was successfully treated with a diet restricted in carbohydrates and frequent meals in small quantities. A 65 years old female presenting with hypoglycemia in the emergency room had the fasting insulin levels of 1,910 µUI/ml. No insulin secreting tumor was detected by images and anti-insulin antibodies were positive. The polyethylene glycol precipitation test showed a basal and after exposition insulin level 1,483 and 114 µUI/ml, respectively. She responded partially to diet and acarbose and required the use of prednisone with a good clinical response.

Determinación de los niveles de cortisol salival en una muestra de sujetos de Santiago de Chile / Salivary cortisol among subjects with and without Cushing syndrome

Background: Salivary cortisol measurement is recommended as a screening mea-sure when a Cushing Syndrome is suspected. Theproposed cut-offpointfor aprobable diagnosis is 0.16 ug/dL. Aim: To determine salivary cortisol concentrations during the day inpatients with and without Cushing syndrome and with depression. Material and Methods: Salivary cortisol was measured by competitive enzyme immuno assay (EIA), in samples obtained at 8:00,15:00 and 23:00 h in 78 patients without Cushing syndrome, aged 40 ± 15years (28 males), 30 patients with depression aged 40 ± 12years (nine males) and four jemales with Cushing syndrome aged 42 ± 17 years. Results: Salivary cortisol was higher among patients with Cushing syndrome than the rest of patients. A salivary cortisol over the cut-off value of O.16 ug/dL was found in 42 percent of subjects without Cushing syndrome and in 33 percent of patients with depression. Median values among patients without Cushing syndrome, depression and with Cushing syndrome were 0.21 (range < 0.1-1.42), 0.2 (range 0,12-0.9) and 0.58 (range 0.37-1.1) ug/dL, respectively Conclusions: Salivary cortisol measured by EIA method was higher among patients with Cushing syndrome but there was a great overlap with values obtained in subjects without the syndrome.

Alta frecuencia de anticuerpos anti-tiroperoxidasa (ATPO) positivos en sujetos adultos, sin patología tiroidea conocida, de Santiago de Chile / Frequency of positive anti thyroid peroxidase antibody titers among normal individuals

Background: Anti-thyroid peroxidase antibodies have a pathogenic role in Hashimoto thyroiditis. Between 10 and 19 percent of individuals without thyroid disease, have positive titers of these antibodies. Aim: To study the frequency of positive titers of anti-thyroid peroxidase antibodies in healthy individuals. Material and Methods: A blood sample, to measure anti-thyroid peroxidase antibodies and thyroid stimulating hormone (TSH) by chemoluminiscense assay, was obtained from 67women and 62 men aged 45 ± 14years, without a personal or familiar history of thyroid diseases and normal thyroid palpation. The cutoff point of the manufacturer to consider positive a titer of anti-thyroid peroxidase antibodies was set at 35 IU/ml. Results: Twenty-eight women and 28 men had positive antibody titers (43 percent of the sample). Subjects in the upper tercile of anti-thyroid peroxidase antibody titers had a higher TSH than those in the second tercile, although within normal limits (1.73 ± 0.74 and 1.37 ± 0.59 mlU/L, respectively p = 0.02) Conclusions: Forty three percent of the studied subjects without personal or familial history of thyroid diseases had positive titers of anti-thyroid peroxidase antibodies. Further prospective studies should evaluate whether this observation discloses an increase in thyroid autoimmune disease in a population with increased iodine intake.