Self-collection by diabetic patients of capillary blood for free insulin monitoring; reduction by diamide of haemolysis-induced insulin loss

Validation of a species-optimized enzyme-linked immunosorbent assay for determination of serum concentrations of insulin in dogs

BACKGROUND

Measurement of canine serum insulin has relied on methods developed to measure human insulin. A species-optimized test for measurement of serum insulin in dogs is now commercially available.

OBJECTIVE

The purpose of this study was to validate the canine ELISA for determination of serum insulin concentration in dogs.

METHODS

Precision was determined by evaluating intra- and interassay coefficient of variation (CV), and accuracy was determined by dilution and spike recovery studies. A method comparison study with samples from 34 clinically healthy dogs and 73 dogs examined for various illnesses and disorders ("patients") was performed using the canine ELISA and an ELISA for human insulin. Biologic relevance of the canine assay was evaluated by measuring insulin in samples collected from 8 healthy dogs after administration of glucagon. A stability study was preformed with 6 samples stored at 20°C, 4-8°C, and -20°C.

RESULTS

For the canine ELISA, intra- and interassay CVs were 4.3-7.8% and 4.4-7.7%, respectively. Mean recovery after dilution was 99% and recovery after spiking with porcine insulin was 116%. The canine and human ELISAs correlated well (r(2) =.94 for healthy dogs, r(2) =.88 for patient samples). After glucagon injection serum insulin concentrations increased significantly in 8 dogs. Insulin was stable for 30 days in 6 serum samples stored at -20°C and in most samples for 8 days at 4-8°C. Insulin was stable for <3 days at room temperature (20°C).

CONCLUSIONS

The new canine serum insulin ELISA had good precision and accuracy and correlated well with the previously used assay.

Hypoglycemia: factitious and felonious

Factitious diseases are characterized by physical or psychologic symptoms that are voluntarily self-induced. These diseases are as old as mankind. Once called "malingerers," these patients must be distinguished from hysterics in whom symptoms are produced unconsciously. In factitious diseases, illness is produced by deliberate acts by the patient who when seeking medical help omits to mention them and may continue strenuously to deny them even when confronted with the evidence. Factitious diseases occur in patients who simulate or exaggerate symptoms or disability to obtain some kind of discernible personal gain or avoid an unpleasant situation; however, such actions may only produce disadvantages by exposing the patient to the risk of death or permanent injury. This has been described as Munchausen syndrome, which is probably a manifestation of severe psychiatric disease. The use of medicines or poisons to induce illness in others also produces a type of factitial disease and presents similar or greater difficulties in diagnosis. In both situations, the clinical history, ordinarily the most important clue to the correct diagnosis, is not only incomplete but often misleading. Sometimes referred to as Munchausen by proxy, this form of factitial disease may be impossible to distinguish from attempted murder or grievous bodily harm. The subtle differences between these disorders, if any, have not been discussed herein.

Finger-prick--an alternative to venipuncture for the assessment of endocrine profiles in women

Traditionally, there has been a reliance on venipuncture to obtain peripheral blood endocrine levels for the assessment of infertility treatment cycles. We have assessed the viability of a finger-prick capillary blood collection method to provide an alternative to venipuncture, assisting in the treatment of patients for whom venous sampling may be difficult to perform. A direct one-to-one relationship was found between the two collection methods with respect to E2, P, and LH measurement. Finger-prick blood collection is simple and easy to perform and provides a viable alternative to venipuncture. It also alleviates the stress involved with multiple attempts at venous sampling in some patients.