Question 24

The specimen must be completely dried before the test can be processed.

For blood spot collections related to inborn errors of metabolism, it is essential that the specimen is completely dried prior to processing. This ensures that the samples are stable and can be accurately analyzed for metabolic conditions.

A) The newborn must be at least 3 days old.

While there are specific guidelines regarding the timing of blood spot testing, this option is not the correct answer. In some cases, testing can occur before the newborn reaches three days, depending on the condition being screened for, making this statement overly restrictive.

B) The circles on the filter paper must be at least half filled.

This option is incorrect because the filling of the circles on the filter paper is not a requirement for the collection of specimens. The quality of the sample is determined more by the drying process and the technique used during collection, rather than the extent to which the circles are filled.

C) The first drop of blood immediately following the puncture must be included.

This statement is misleading. The first drop of blood is often not used in blood spot collections as it may contain tissue fluid and is not representative of the systemic circulation. Therefore, this option does not align with best practices for blood collection.

D) The specimen must be completely dried before the test can be processed.

This is the correct answer as complete drying of the blood specimen is crucial for the accuracy of the tests conducted on it. Dried specimens minimize the risk of contamination and degradation, ensuring reliable results in metabolic testing.

Conclusion

The necessity for the specimen to be completely dried before processing is vital for accurate diagnostic outcomes in inborn errors of metabolism testing. Options A, B, and C do not satisfy the critical requirements for effective blood spot collection, thereby reinforcing that D is the definitive correct choice. Proper adherence to specimen handling protocols, including drying time, is essential for successful laboratory analysis.