Final answer:
Vitamin B is not measured in international units. International units are used for substances like heparin, insulin, and vitamin E. Vitamin B doses are usually specified in milligrams or micrograms.
Step-by-step explanation:
The medication among the options provided that is not measured in international units is vitamin B. International units are used to measure the potency of certain medications and vitamins, such as heparin, insulin, and vitamin E. However, vitamin B is not typically measured in international units because it is water-soluble and its activity or potency is not standardized in the same way as some other substances. For water-soluble vitamins, doses are usually given in milligrams or micrograms.
As for the related information provided, vitamin C is an example of a water-soluble vitamin, while phosphorous is an example of a nutrient that is stored in the body. The hormone produced by the kidney that stimulates red blood cell production is called erythropoietin, not thrombopoietin or vitamin D.