A pediatrician suspected my son had leukemia. Turns out he was just drinking way too much cow's milk.

• At a routine checkup, my son's pediatrician said she was concerned about how pale he looked.
• More tests showed that he was severely anemic, which required iron transfusions.

"The good news is your son doesn't have leukemia!"

My toddler's pediatrician called first thing on a Friday morning to deliver this news. During a recent checkup, the doctor had expressed major concern about Johnny's pale complexion, which I'd always attributed to living in the Pacific Northwest and being the product of two very Irish parents.

He underwent a complete-blood-count panel, the results of which pointed to a severe iron deficiency. His hemoglobin level was between 4.5 and 5.6; the normal range for a 2 year old was 10.9 to 15. His anemia was so bad that he'd developed an accompanying heart murmur.

I was surprised when the doctor said she'd secretly feared leukemia, but that's how sick Johnny looked. The culprit, thankfully, was not blood cancer but cow's milk. He received his first iron transfusion right away and got his second and final one the next week. He also started taking iron supplements every other day.

A lot of people don't know this, but too much milk can be a bad thing

Johnny was born during the first year of the pandemic, so my stress level was high for a long period. I was awaiting my older son's inevitable autism diagnosis and adjusting to a new city after an interstate move. So when Johnny started drinking cow's milk at the age of 1 and never wanted much of anything else, I didn't try to correct his behavior. I kept pouring to keep the peace.

Johnny drank about 30 to 40 ounces of milk a day, much higher than the 16 to 24 ounces recommended for his age group. I didn't know that calcium can suppress iron absorption, so any iron that made it into his body would've immediately been trampled by excess dairy.

I didn't think milk could affect him so much

Sure enough, he was always in a sour mood, never seemed well rested, and had nearly constant meltdowns. I thought that maybe he had just started the terrible twos ahead of schedule, or that he was becoming an overindulged youngest child, or that he, too, was on the autism spectrum.

Johnny had been a colicky infant, so I found myself Googling whether colic can return in the toddler years. I suspected he drank too much milk, which was filling him up, but I didn't realize excessive intake could do so much damage. After all, the US has pushed milk consumption for decades — I grew up seeing "Got Milk?" ads on TV and billboards, and my dad always encouraged me to drink lots of it to get taller and stronger.

Johnny's hematologist said most parents are unaware that too much milk can be a problem. We see our kids every day, but infrequent visitors such as a doctor or relative can notice worrisome physical changes in our little ones.

The hematologist also told me that most children are completely different people after recovering from anemia, which can cause headaches, weakness, fatigue, and a host of other maladies. Johnny constantly felt like garbage but had no way of telling me. My husband and I regret assuming that Johnny was moody when his heart was quite literally distressed.

Johnny recovered from his heart murmur and anemia a month and a half into treatment. Everyone in our lives observed an immediate improvement in his disposition. Now he has the willingness and energy to eat, smiles at everyone he sees, and wakes up talking eagerly to his stuffed animals — a stark contrast to when he'd start and end his days in tears.

For the first time in his little life, I feel like I'm finally getting to know the real Johnny.