[Reference ranges of insulin, insulin like growth factor-1 and adrenocorticotropic hormone in ponies].

This study validates a type of testing for hormones in ponies and establishes reference ranges for three specific hormones. The testing protocol was found to be effective and offered new insights into age-dependent hormonal differences in ponies.

Methodology

• The researchers aimed to validate a test, called a chemiluminescence immunometric assay, that was conducted using IMMULITE 2000®. This test was used to determine the levels of three hormones: adrenocorticotropic hormone (ACTH), insulin, and insulin-like growth factor-1 (IGF-1) in ponies.
• Blood samples were collected from 130 ponies, ranging in age from 3 to 32 years, in the afternoon to standardize the procedure.
• The reference ranges for hormone levels were calculated according to an international standard, the Guideline EP28-A3C of the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) from 2010.

Results

• The study found that there was minimal daily variation in the levels of the three hormones, 3.28% for insulin, 3.35% for ACTH and 1.84% for IGF-1, indicating a strong degree of reliability in the method of testing.
• The interday precision, which indicates the variability of measurements taken on different days, also showed consistency with relatively low percentages, implying that hormone levels did not change significantly between days or after being stored at cold temperatures.
• The researchers found that the reference ranges for insulin and IGF-1 levels in pony blood are not dependent on age, while the level of ACTH does change dependent on the age of the ponies. Younger ponies aged 3-12 years showed a lower reference range (4.2-19.8 pg/ml) than ponies aged 13-32 years (5.0-22.6 pg/ml).

Conclusions

• The test method was deemed suitable for determining ACTH, IGF-1, and insulin in pony serum. However, it was noted that the lowest detection limit for insulin is 2.0 mU/l.
• The established reference ranges for insulin and ACTH can be helpful in diagnosing and monitoring conditions such as equine metabolic syndrome and pituitary pars intermedia dysfunction (PPID) in ponies.