Overlooked Diagnostic Test for Blood Calcium Levels Leads to Rare Diagnosis

A 23-year-old presents to the emergency department with progressive symptoms. It starts with tingling in the fingertips that lead to leg cramps that turn into feeling like she’s turning into stone, frozen in one position with stabbing pain. And perhaps most troubling, she can't concentrate. In fact, the brain fog is so severe that she’s afraid to drive.  

Over the course of three days, her life has been turned upside down. 

She takes a taxi to the emergency department and is seen after waiting six hours. She provides a quick medical history, noting she recently had neck surgery for parathyroid overactivity — an important clue to her diagnosis. 

Parathyroid glands produce parathyroid hormone that regulates the blood calcium level, which maintains bone strength and helps muscles and nerves function. Calcium levels in the blood have to be kept at a very specific level. Just like in your physiology lectures: HYPERcalcemia and HYPOcalcemia. And calcium levels that are either too high or too low can be deadly. 

But in moving quickly in the emergency department, testing for serum calcium is overlooked. A patient with recent neck surgery has symptoms consistent with low blood calcium levels —  why not check her calcium? 

It’s true that in a chaotic ER things can be overlooked. But a lot of time, calcium isn't ordered because it's not part of the regular "electrolyte” or “chemistry” panel — it has to be added specifically. With computer systems and the way test panels like these are built, they can shape the thinking of physicians, putting certain symptoms front of mind, while others might get neglected. 

Fortunately, a diagnosis was caught early enough for this patient that no long-term damage was done. But this case serves as a reminder that although rare diseases are rare, it doesn’t mean as a healthcare professional, you’ll never encounter them.