Considering the type of work your husband is in, it is perfectly reasonable for the employer to insist on random drug screens. His employment contract should clearly spell this out (you should read it carefully and make sure). Once the employer receives a positive reading, you must assume they are going to make inquiry to ensure the employee is not abusing some elicit substance. It is reasonable for the employer to ask for levels to insure your husband is not abusing his prescription in such a way as to place himself and others at risk. Again, it is reasonable and is likely spelled out in his employment contract.
You should read his contract carefully. It should spell out the rights of both parties in this situation. This really isn't a HIPAA issue as he will be providing the information himself. Whether or not they can force him to provide it will depend on the language of his contract, but I predict that they can.
If he had no employment contract then the employer would have every right to take these steps and his refusal to provide the "numbers" could easily lead to his immediate termination. Therefore, unless the employer's actions violate his employment contract then he will need to comply with their requests or risk losing his job.
Please reply if I can help further.
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