Complete laboratory diagnosis of Insulin Autoimmune Syndrome.

The definition of Insulin autoimmune syndrome includes the presence of high levels of blood insulin and insulin autoantibodies. We encountered a 45-years-old white man with a high insulin serum value that do not fit with the C-peptide result. To discard or to confirm an analytical interference and diagnose a possible Insulin Autoimmune Syndrome we performed the following investigations: dilution linearity test, heterophilic antibody blocking, polyethylene glycol precipitation, measurements with alternative assays, and gel filtration chromatography by size exclusion. The latter technique confirmed that most of the insulin was complexed with a 150-kDa protein, corresponding to immunoglobulin G, identified as insulin autoantibodies. These antibodies were responsible for hypoglycemia attacks in the patient, who had a previous autoimmune disease. This case highlights the importance of carefully analyzing the results and ruling out possible interferences, as well as considering all kinds of pathologies, even if they are infrequent.

Macroprolactin: From laboratory to clinical practice.

Prolactin measurement is very common in standard clinical practice. It is indicated not only in the study of pituitary adenomas, but also when there are problems with fertility, decreased libido, or menstrual disorders, among other problems. Inadequate interpretation of prolactin levels without contextualizing the laboratory results with the clinical, pharmacological, and gynecological/urological history of patients leads to erroneous diagnoses and, thus, to poorly based studies and treatments. Macroprolactinemia, defined as hyperprolactinemia due to excess macroprolactin (an isoform of a greater molecular weight than prolactin but with less biological activity), is one of the main causes of such erroneous diagnoses, resulting in poor patient management when not recognized. There is no unanimous agreement as to when macroprolactin screening is required in patients with hyperprolactinemia. At some institutions, macroprolactin testing by polyethylene glycol (PEG) precipitation is routinely performed in all patients with hyperprolactinemia, while others use a clinically based approach. There is also no consensus on how to express the results of prolactin/macroprolactin levels after PEG, which in some cases may lead to an erroneous interpretation of the results. The objectives of this study were: 1. To establish the strategy for macroprolactin screening by serum precipitation with PEG in patients with hyperprolactinemia: universal screening versus a strategy guided by the alert generated by the clinician based on the absence or presence of clinical symptoms or by the laboratory when hyperprolactinemia is detected. 2. To create a consensus document that standardizes the reporting of prolactin results after precipitation with PEG to minimize errors in the interpretation of the results, in line with international standards.

Macroprolactin: From laboratory to clinical practice. / Macroprolactina: del laboratorio a la práctica clínica. Recomendaciones del grupo de trabajo de laboratorio de la SEEN y de la comisión de hormonas de la SEQCML sobre la medición e informe del resultado de la macroprolactina.

Prolactin measurement is very common in standard clinical practice. It is indicated not only in the study of pituitary adenomas, but also when there are problems with fertility, decreased libido, or menstrual disorders, among other problems. Inadequate interpretation of prolactin levels without contextualizing the laboratory results with the clinical, pharmacological, and gynecological/urological history of patients leads to erroneous diagnoses and, thus, to poorly based studies and treatments. Macroprolactinemia, defined as hyperprolactinemia due to excess macroprolactin (an isoform of a greater molecular weight than prolactin but with less biological activity), is one of the main causes of such erroneous diagnoses, resulting in poor patient management when not recognized. There is no unanimous agreement as to when macroprolactin screening is required in patients with hyperprolactinemia. At some institutions, macroprolactin testing by polyethylene glycol (PEG) precipitation is routinely performed in all patients with hyperprolactinemia, while others use a clinically based approach. There is also no consensus on how to express the results of prolactin/macroprolactin levels after PEG, which in some cases may lead to an erroneous interpretation of the results. The objectives of this study were: 1. To establish the strategy for macroprolactin screening by serum precipitation with PEG in patients with hyperprolactinemia: universal screening versus a strategy guided by the alert generated by the clinician based on the absence or presence of clinical symptoms or by the laboratory when hyperprolactinemia is detected. 2. To create a consensus document that standardizes the reporting of prolactin results after precipitation with PEG to minimize errors in the interpretation of the results, in line with international standards.

Serum 25-hydroxyvitamin D in early autumn to ensure vitamin D sufficiency in mid-winter in professional football players.

BACKGROUND & AIMS: There is growing awareness that vitamin D sufficiency is required for overall optimal health. Most experts agree that 25-hydroxyvitamin D levels of at least 75 nmol/L, as sufficient vitamin D status. Our aim was to investigate the serum 25-hydroxyvitamin D concentration required in mid-October to ensure vitamin D sufficiency in early February, and to assess the rate of vitamin D insufficiency in both seasons. METHODS: We measured serum 25-hydroxyvitamin D, parathormone, and other related biochemical parameters, in a sample of 28 professional football players homogeneous in factors influencing serum 25-hydroxyvitamin D concentration in a sunny area of southern Spain. RESULTS: The serum 25-hydroxyvitamin D concentration of 122.7 nmol/L was required; 14.3% reached this level. Ninety-three percent had levels ≥75 nmol/L in mid-October, and 64% had levels <75 nmol/l in early February (χ(2) test, ρ = 0.001). CONCLUSIONS: Despite the homogeneity in sunlight exposure and vitamin D intake few football players reached the level ensuring vitamin D sufficiency in mid-winter, and two thirds had vitamin D insufficiency in early February. Given our findings, it would be advisable to assess the vitamin D levels in early autumn, although additional studies are necessary.