2.5 year old falling off the charts, when to worry?

[ivymae]

My 2.5 year old weighs 20lbs (not even on the charts), and hasn't gained since she was 12 months old. Up until recently i didn't think much of it, since I'd been told that a lot of kids plateau and just redistribute weight during their second year, but now that she's fallen off the charts for height as well (32 inches), i'm trying not to get anxious.

My older daughter is tall and thin (90th for height, 50th for weight) and my youngest is above the 90th percentile for weight and height, so the fact that the baby is about to outgrow the toddler has me consulting Dr. Google, and that's just not a productive route. We have an apt with our (wonderful) pediatrician next month for a WBV for all the girls, but I just ran the numbers today and am trying to decide whether or not to reschedule for sooner. If it does sound unusual, are there specific tests i should ask for?

She's generally a pretty normal kid - developmentally on track, energetic and bright eyed - so maybe she's just a tiny person? I'd like to eventually out away the 18 month clothes though...

[RosemaryS-F]

Hey, my DS is about 23lbs; He still wears his 3-6 month old bathing suit that he has had all his life (he is a march 08 baby.) I would worry in your place though; not to be discouraging, and for no other reason than that I worry about it and I don't blame YOU for worrying. I would reschedule the visit since you like your ped. I would do what they advise within reason. I would do it because it would ease my mind. Have you thought about gluten allergies?

[tylerdylan]

It is always concerning when a child stops following a curve and starts to drop off the charts. My DS did this too. He was 19.5 pounds at 8 months and at 3.5 years was only 21.5 pounds. He looked horrible (skinniest kid I've ever seen). We could not get him to gain weight no matter what we did and both height and weight were far off the charts. No one could figure out what was wrong with him - all standard tests came back negative. We finally got a diagnosis when he was 3.5 - brainstem tumour. Following his surgery he woke up with an appetite and started packing on the pounds. He had 16 months of chemo and now is a happy healthy 5 year old who has caught up to his peers. He's about 42 pounds and looks great.
I would probably change the appointment and get the tests underway as it will likely take some time before you get any answers one way or the other.