-- and he continues to be a healthy, strapping young lad. However, we did run into one health hiccup: he failed the State Newborn Screening for thyroid function.
Let's take a step back. For those unaware, each state has a Newborn Screening (NBS) program in place to a number of detect treatable metabolic and endocrine conditions. In most states, the endo diseases checked for include CAH (Congenital Adranal Hyperplasia) and hypothyroidism. Hypothyroidism is a big deal in infants, because left untreated a baby with inadequate thyroid hormone production will have abnormal development on several fronts, including growth and brain development. A severely deficient infant -- left untreated -- will have cognitive deficits that are completely avoidable if thyroid hormone is started in a timely manner. There are also other potential issues, like problems with growth, feeding (constipation), prolonged jaundice, and temperature instability.
There are multiple reasons to have a thyroid hormone deficiency/issue in infancy, and an in-depth discussion is beyond the scope of this blog post. However, the most common reasons are:
a) small, displaced, or absent thyroid gland
b) temporary issue caused by antibodies produced by mom that crossed into baby's bloodstream
c) enzyme defect impacting one of the steps in thyroid hormone synthesis and release
The NBS is designed to be highly sensitive. In other words, there are plenty of false positives, and even a mild thyroid defect/abnormality may show up, because it's better to detect more babies than to miss treating someone who would benefit. I know plenty about congenital hypothyroidism, because I've seen many babies who failed their state screens over the course of my training and practice. I love to tell parents that it's the best thing to be diagnosed with, because it's entirely treatable and has essentially no consequences if managed appropriately.
I still was completely shocked to receive a phone call when C was 1 week old from the state screening lab. I actually let it go to voicemail -- an unidentified number interrupting me during an all-important chest-napping session? NOOO thanks. But a few moments later I was curious, so I played the message.
"Dr. SHU? This is Dr. X calling from the University of Miami department of pediatric endocrinology. Um, I'm calling about your baby. Can you give me a call back?"
I admit that my first reaction was HOW DARE THEY CALL ME ON MY LEAVE when I am with my 1-week old! Then I realized. "Your baby" was not in reference to one of my patients. She was referring to MY baby, i.e. the one currently on my chest. I called her back.
She was very nice and told me that C's TSH was in the high 30s on day of life 1, and then rose to 41 on day of life 4. TSH is made in the pituitary (the body's "master gland", located in the brain behind the nose), and high TSH can mean that the thyroid gland itself is having trouble making enough thyroid hormone to satisfy the body. A high TSH in the first 24 hours of life is no big deal -- often it's just detection of a normal or slightly exaggerated 'birth surge'. But the number shouldn't continue to rise. Thus began our little adventure, consisting of one visit to my own clinic (because I felt like I should do things the 'official' way), 4 more lab draws over the course of 6 weeks, and one thyroid ultrasound.
His numbers kept looking borderline, but ultimately did not normalize in time (for those curious, his TSH dipped to 13, then was 7, then 8, and then 9, while free T4 dropped to the low end of the normal range). 2 weeks ago, he started on levothyroxine at a low dose, and yesterday his lab checked revealed normal numbers for the first time.
I'm sure I'm not the first specialist to have their child diagnosed with a condition in their specialty -- but it was still completely unexpected and continues to feel sort of surreal. I mix up his medicine every morning just as I had instructed parents to do so for years -- except until now, I never actually tried crushing up the little tablets, mixing with pumped milk, and giving the mixture with a syringe (note: it's actually not hard and works just how I learned to describe it to parents. whew!). I had never trekked back and forth for multiple lab draws where I had to watch my little one scream as his foot was pricked yet again (at this point, he gets the warmer put on and starts to freak out, because I think he has learned what is coming). I had never waited anxiously for results, hoping the whole thing would just blow over and we could forget about it.
Now I know what it all feels like, and it has been stressful at times. I don't like giving my tiny 8-week-old medicine every day. I don't like subjecting him to the pain of repeat blood draws. And I don't like worrying about whether his levels are normal. And all of that stress is with what is the best diagnosis in pediatric endocrinology. (I still maintain that it is!! Treatable, relatively straightforward, and with minimal maintenance other than a pill daily. I feel so lucky that this is all we have had to deal with!).
ANYWAY. It's hard for me to say what I've learned in the ordeal, because I don't feel like this has been a real 'patient' experience -- I feel like I'm more in a hybrid Dr/Parent role since I know so much about the condition and have my own interpretation of his results. But I still feel that I've gained a bit more empathy for my patients, particularly the parents of newborns who receive news that their completely-normal-appearing infant has some potential problem that requires medication. Forgive the pun, but this news can be a hard . . . pill to swallow (for the parent, not the child!). I think in the future I will still reassure parents, but also give them a little more space to react to the diagnosis. I also think I need to acknowledge that it can be very hard to comply with any daily prescribed regimen without a miss -- so far C has gotten every prescribed dose (I have a checkbox in my planner for it!), but some have been given later than others.
The endpoint for C's treatment? Based on his response thus far, he'll likely be on the medication until at least age 3, and then we'll do a trial off to see if he can maintain normal levels on his own. Treatment is conservative until 3 because that is the critical window for brain development, so it's just not worth it to experiment with stopping the meds before then. I still don't know the cause of his borderline levels -- I have no known thyroid history (so antibodies less likely), and his thyroid looked normal on ultrasound. Perhaps I do have antibodies that I don't know about (in which case this should completely resolve for him!) or he has a mild enzymatic defect.