What was the matter with Tim, anyway?

Dickens himself doesn't specify what disease Tiny Tim has, only symptoms of him using a crutch and being expected to die within a year if untreated. There's been plenty of speculation with the following four suggested and renal tubular acidosis the most likely:

Renal Tubular Acidosis:

This is a disease where the kidneys fail to excrete acids into the urine, causing them to build up in the blood. It can result in growth retardation, bone disease, and progressive renal failure. It's fatal if left untreated but even back in Dickens' day, doctors would have been able to provide medicine in the form of frequent doses of alkaline solutions to neutralize the acid. The proper treatment (which Scrooge could have funded) would result in a full and rapid recovery. This fits in with all Tim's symptoms plus a complete, speedy cure that Scrooge could have provided.

Rickets:

This disease is caused by vitamin D deficiency and has symptoms of soft bones, muscular weakness, osteoporosis, and joint pain. Without vitamin D, the body cannot absorb calcium needed for building and maintaining strong bones. The body produces vitamin D when exposed to direct sunlight so rickets was a common problem in cities with heavy smog blocking the sun, as in late 1800's London. This vitamin is also found in such natural foods as fatty fish species, eggs, and beef liver. Vitamin D wasn't discovered until the early 20th Century but they might have unknowingly treated Tim's condition by the better foods that Scrooge could have provided.

However, it would seem likely that if Tim had rickets, his siblings also living in smog and having poor nutrition, would have been afflicted too. Also, rickets is rarely fatal and Tim was expected to die before long if untreated.

Tuberculosis:

This was a very common disease at the time, typically respiratory in adults but it could appear in children as a crippling illness also causing fatigue and weight loss. Left untreated, it would have eventually killed Tim. Scrooge might have helped by providing a back brace and better nutrition, saving Tim's life and causing a remission in his disease.

Dickens himself states only that 'Tiny Tim did not die', not specifying whether he simply survived or was completely cured. He would never have been completely cured of tuberculosis and wouldn't have been able to run into Scrooge's arms, as many film versions show at the end.

Polio:

Spinal polio can cause asymmetric paralysis involving the legs, hence the crutch, but this type of polio is rarely fatal. There is no real cure and treatment is often long term, involving physical therapy, braces, corrective shoes, and sometimes orthopedic surgery. The story doesn't imply any difficult or lengthy treatment.

Here are some relevant web sites for anyone wishing to read further:

http://www.msnbc.msn.com/id/22359312/

http://www.fidnet.com/~dap1955/dickens/christmas.html

http://www.mccarter.org/Education/Carol-08/html/4.html

http://community.seattletimes.nwsource.com/archive/?date=19921215&; slug=1530168