I want to take citracal slow release. would the 24 hour release effect of the calcium cause an interaction with my levothyroxine?

Sometimes: The decrease in thyroxine absorption was done with short acting calcium carbonate. To be safe do not take them at the same time.

Check it out: You can use a drug interaction checker whenever you have questions about drug-drug interactions or drug - food interactions. Here is 1 option (Drugs.Com): https://www.drugs.com/drug_interactions.php Your pharmacist is also a good source of info.