Read about keratosis pilaris, which is a common, harmless condition where the skin becomes rough and bumpy, as if covered in permanent goose pimples.
Read about Klinefelter syndrome - a condition in which male babies are born with an extra X chromosome. Find out about the symptoms, causes and treatments.
Sudden knee pain is often caused by overusing the knee or injuring it. Find out what you can do to treat it yourself and when to get medical help.
NHS information about knock knees, including symptoms, treatments and what to do if you think you or your child have it.
Kawasaki disease is a condition that mainly affects children under the age of 5. It's also known as mucocutaneous lymph node syndrome.
A kidney infection (pyelonephritis) is a painful and unpleasant illness caused by bacteria travelling from your bladder into one or both of your kidneys.
Information about kidney stones, including symptoms, causes, treatment and prevention.
Read about how an anterior cruciate ligament (ACL) injury is caused, and the considerations when deciding whether to have reconstructive surgery.
Kyphosis is a condition where the top of the back is excessively curved and appears more rounded than normal.
A knocked-out tooth can usually be saved by putting it back in place or in milk as soon as possible, before seeing a dentist.
Read the NHS information about keloid scars, including symptoms, treatment, causes and when to get help.
Find out about kidney cancer, including the symptoms, causes, tests, treatments, and where to get support.
Find out what a knee replacement involves, when it might be recommended, and how it can help with knee pain and movement.