Part 2 Differentiating Primary Hyperparathyroidism from Familial Hypocalciuric Hypercalcemia: FHH CASE STUDY

Our guest blogger, Dr. Kevin Parrack, a surgeon from the Norman Parathyroid Center, educates us about differentiating Primary Hyperparathyroidism (pHPT) from Familial Hypocalciuric Hypercalcemia (FHH) in this two-part series. 

Part 2 below focuses on the practical application of differentiating pHPT and FHH though a case study. Did you miss Part 1? Here is the link to Part 1 where Dr. Parrack discusses the important differences between the two conditions.

———————————————————————————————————————————————————–

One of the questions I get asked frequently is whether or not to get urinary studies on patients with primary hyperparathyroidism. These studies have their place, but you have to understand the details to know if they will be useful in a specific situation, and what to do if you have results you didn’t ask for. The following case is an excellent illustration of these issues.

This is one of our patients we operated on who has given our center permission to tell her story. I have changed her name (we’ll call her Bee) and certain details to protect her privacy. She hopes that telling her story can help other people dealing with the same thing. 

Patient Profile

Bee is in her 40’s and had been struggling with a number of symptoms that she did not expect at such a young age and in what she thought was good health. Bee was tired most of the time regardless of how much she slept, began having headaches that worsened over time despite treatment, as well as new onset joint pain and palpitations. The patient didn’t have any known medical disease to explain these problems and these symptoms certainly seemed beyond just typical aging so she saw her doctor for help.

Primary Care 

Bee’s primary care physician listened to her concerns and checked a number of labs as a first step.  Her PCP noticed the high calcium level (10.6 mg/dL) and checked her PTH level (99.8 pg/mL). Bee’s calcium level was high for her age at 10.6 mg/dL, and with this elevated calcium level, the PTH level should have been suppressed, and therefore low, if her parathyroid glands were normal. The fact that the patient’s PTH was high at 99.8 pg/mL with elevated calcium, this corresponds to roughly a 99% chance of having primary hyperparathyroidism. 

This PCP realized that Bee had primary hyperparathyroidism and referred her to a local endocrinologist for advice on how to proceed.

Referred to Endocrinologist

The endocrinologist ordered a 24 hour urinary study and the results showed a 24 hour urinary calcium level of 14.9 mg/24 hours and a Calcium : Creatinine ratio of less than 0.01.  If you look these values up you will see that they are consistent with FHH, which stands for Familial Hypocalciuric Hypercalcemia. This is a benign genetic condition for which surgery is not routinely indicated, as surgery will not improve the calcium level and there are no associated symptoms that need to be fixed.

After getting the urinary study results the endocrinologist told her that she had FHH; therefore did not have primary hyperparathyroidism and should not have surgery.

Patient’s Self-Advocacy Pays Off

Bee researched this issue on her own and after reading primary articles in a university library about FHH realized that she probably did not have FHH and that her urinary studies represented what is known as a “false positive.”  She contacted our center and discussed her case with one of our surgeons.

FHH is a rare disorder but it does happen. We speak with so many hypercalcemic patients that we come across it from time to time, but not often.  FHH and primary hyperparathyroidism present in different ways and have different characteristics, which I discuss in Part 1 of this blog series.

FHH and primary hyperparathyroidism present in different ways and have different characteristics…

Unfortunately the urinary studies are not perfect, they make mistakes.  Some patients who have primary hyperparathyroidism have urinary studies that look like FHH!  In other words, if you check urinary studies in every person who has primary hyperparathyroidism, you will find some urinary studies that look like FHH. If you then tell the patient not to have surgery, you are condemning them to keep a tumor that can make them miserable and sick.  This is something we take very seriously.

Key to spotting FHH

The key to spotting FHH and avoiding operating on those patients if possible is to understand the difference in how FHH and primary hyperparathyroidism patients present, and to know what to do if you suspect FHH.

FHH is a genetic disorder that will affect about half of the family members without skipping generations.  People with this problem will have high blood calcium levels but no symptoms or complications.  Their calcium levels may also have been slowly but steadily rising for their entire life. If I have a patient with a family history that makes me suspicious of FHH, there is a protocol in place for how to evaluate the family, not just the individual patients, which includes comprehensive genetic testing. This is not a disorder that you usually find in one person; it is a family diagnosis.

If I have a patient with a family history that makes me suspicious of FHH, there is a protocol in place for how to evaluate the family, not just the individual patient, which includes comprehensive genetic testing. This is not a disorder that you usually find in one person; it is a family diagnosis. 

No one in Bee’s family had high calcium levels; she had calcium levels in the 9’s a few years ago, and typical symptoms of primary hyperparathyroidism with no other explanation, so she didn’t think she had FHH.  When Bee spoke with us her case sounded like routine primary hyperparathyroidism and we explained that we wouldn’t have obtained urinary studies for her due to the concern of a false positive preventing a curative surgery. With the unwanted urinary study results in hand we explained that we still thought she had primary hyperparathyroidism, but that there was a small chance that she had FHH. However, that would require the genetic mutation happening in her first in the family, which is pretty unlikely. because leaving a parathyroid tumor in is far more dangerous than an expert surgeon examining the parathyroid glands in a patient with FHH, she chose to have parathyroid surgery.

Because leaving a parathyroid tumor in is far more dangerous than an expert surgeon examining the parathyroid glands in a patient with FHH, she chose to have parathyroid surgery.

Surgical Outcome

In her surgery we found a single parathyroid adenoma and three small parathyroid glands. These findings are consistent with long-term primary hyperparathyroidism where one parathyroid tumor is the problem and the other three parathyroid glands have been suppressed for a long period of time. In FHH all of the parathyroid glands are typically enlarged, some more than others. In the recovery room her PTH dropped down to normal, consistent with being cured of primary hyperparathyroidism and not typical with FHH.  

Needless to say we are all very happy for Bee and wish her the best. I also appreciate her very much for letting us share her story because of all the types of patients I see, the stories that upset me the most are the people with primary hyperparathyroidism that go undiagnosed for decades and wind up with a complication that could have been avoided. Urinary studies can be very useful when used as part of a workup for a family we suspect has FHH, but in an individual person who has routine primary hyperparathyroidism, these studies can cast doubt on an obvious diagnosis. 

Dr. Kevin Parrack M.D., FACS

Dr. Kevin Parrack is a surgeon at the Norman Parathyroid Center, a high volume parathyroid practice that treats around four thousand parathyroid patients per year. In this role Dr. Parrack focuses on teaching patients and physicians about parathyroid disease in hopes that more people will become familiar with this problem and therefore fewer people will suffer from it without appropriate treatment.

Dr. Parrack obtained his undergraduate degree at NYU before graduating from Stony Brook School of Medicine. He completed his residency program at Columbia Presbyterian in Manhattan and the endocrine surgery fellowship at the Cleveland Clinic. His focus on teaching began in college, where his first career was in test prep for the medical school entrance exam. Throughout his training Dr. Parrack worked on admissions and academic committees, designed curriculums and teaching aids, and that interest carried into his role as a surgeon. Before coming to the Norman Parathyroid Center Dr. Parrack was a faculty surgeon at Columbia where he was the director of the Thyroid Biopsy Center and managed outreach to the community to increase awareness regarding endocrine disease.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s