Katie Price's son has been diagnosed with a condition which causes ''angry outbursts''.

The model-and-author's eldest child, 10-year-old Harvey - whose father is her former boyfriend Dwight Yorke - suffers from numerous health and behavioural disorders and is now preparing to start a course of medication to tackle a new problem.

Katie - who also has son Junior, seven, and daughter Princess, five, with ex-husband Peter Andre - said: ''My son Harvey has been diagnosed with another condition this week.

''He already suffers from septo-optic dysplasia, which causes blindness and growth hormone deficiency, Prader-Willli syndrome, a genetic disorder that means he is likely to eat to excess and is prone to obesity and diabetes, as well as ADHD and autism.

''Now a top professor has told me he has also got oppositional defiant disorder, which causes his angry outbursts.

''He is about to start taking an anti-hyperactivity drug called Ritalin.''

Katie - who recently married third husband Kieran Hyler - also revealed years of changing her hair colour have taken their toll on her locks and she is losing her tresses.

She added in her column for The Sun newspaper: ''Poor January Jones - I know exactly how she feels. The 'Mad Men' actress has admitted her hair is falling out in clumps after years of dying it too often.

''I'm a typical, impulsive Gemini, so when I want to go from black to blonde or vice versa, I don't do it gradually as I should but immediately. Now my hair is burned. I should have it cut short and let it recover but I'd feel too much like a boy.

''The moral to this story is; Keep away from extreme hair dye. A tragic situation lurks beneath my extensions.''