Renal tubular acidosis describes a group of syndromes where the kidneys fail to properly filter acid from the body, resulting in the blood becoming too acid (acidosis). It can be caused when the kidneys do not have enough bicarbonate ions to neutralize the acid, or when the kidneys fail to excrete acidic ions. Although acidosis is typical of patients with kidney failure, renal tubular acidosis describes when the blood remains acidic even though the kidneys are otherwise functioning normally.
The causes of most forms of the condition are poorly understood, although they do present with a consistent set of symptoms. One thing that is known to cause the condition is a deficiency of or resistance to aldosterone. This can be caused by the use of certain types of pharmaceuticals.
The disease was not well understood until the mid 20th century, but its symptoms were known to medicine and in popular culture well before then. It has been noted that the condition fits the symptoms being suffered by Tiny Tim in Charles Dickens' A Christmas Carol, particularly the weak bone structure. Dickens' work is also known for presenting people other people with common conditions that were poorly understood in his day.