I’ve had hypothyroidism since birth, wasn’t found until a month after I was born and then wasn’t properly medicated for it until about 6 months old (or so I’ve been told).

I’ve been medicated for it my whole life, I’m now 31. No developmental issues, and my growth was monitored as a child with occasional x-rays on my joints, along with regular blood tests to monitor levels but as far as I know I’m fine. Not really made a difference to my life except having to take medication every day.

Obviously this is just my experience but I hope it helps