When Lara Pitt told doctors she was experiencing extreme fatigue, the Fox Sports presenter was turned away, and told it was nothing more than the stress of being a new mum.

Now, writing for Body & Soul , the 35-year-old has opened up about the hidden illness that arose after the birth of her first son, Lachlan. The disease which was only brought to her attention by, well… a troll.

“Sometimes Twitter can be a cold, harsh place. Other times it can unlock the mystery around a nagging health problem,” the mum-of-two wrote.

“Yep, I owe one helpful tweeter for pointing out – I didn’t have post-natal anxiety or depression, but in fact another post-partum health issue, commonly misdiagnosed.”

The NRL commentator’s symptoms included a heightened heart rate, restless sleeps, fatigue, breathlessness and excess sweating. Then, one day after work, a peculiar tweet caught her eye.

“Does Lara Pitt have an Adams Apple?” it read. Within days, she had noticed “a visible lump was sticking out of my neck, in a sort of heart-like-shape.”

“Some blood tests and an ultrasound revealed I was suffering post-partum Thyroiditis – a condition which occurs in 7-8 per cent of women approximately one to four months after delivery,” Lara said.

"Some blood tests and an ultrasound revealed I was suffering post-partum Thyroiditis." (Image: Getty)

In layman's terms, when the thyroid gland produces too much or too little of the thyroid hormone, thyroiditis occurs. For months, Lara was "swinging" between too much (hyperthyroidism) and too little (hypothyroidism).

"For a few months I’d be depressed, lethargic, and not produce enough breast milk. Then I’d go the other way - feel anxious, have an increased heart-rate, go through rapid weight loss and poor sleep," she wrote.

With help from her husband, an endocrinologist, an osteopath, a refreshed exercise regime and nutrition plan, Lara managed to tackle the condition head on and made a full recovery.

LISTEN: Bec Judd and Monique Bowley discuss month four of having a baby. (Post continues...)

The popular sport personality is now concerned other mothers - who may be suffering post-partum mental health problems - are "getting misdiagnosed or not diagnosed at all."

"If you have a feeling something isn’t quite right, a simple blood test can set things straight," she urges women.

Have you been misdiagnosed post-partum? Share your stories with us below...