VII. Oxaluria. 

Oxalic acid occurs in the urine, in combination with lime, forming an oxalate which is held in solution by the acid phosphate of soda. About .01 to .03 gramme is excreted in the day. It never forms a heavy deposit, but the crystals— usually octahedra, rarely dumb-bell-shaped— collect in the mucus-cloud and on the sides of the vessel. The amount varies extremely with the diet, and it is increased largely when such fruits and vegetables as tomatoes and rhubarb are taken. It is also a product of incomplete oxidation of the organic substances in the body, and in conditions of increased metabolism the amount in the urine becomes larger. It is stated also to result from the acid fermentation of the mucus in the urinary passages and the crystals are usually abundant in spermatorrhoea. When in excess and present for any considerable time, the condition is known as oxaluria, the chief interest of which is in the fact that the crystals may be deposited before the urine is voided, and form a calculus. It is held by many that there is a special diathesis associated with this state and manifested clinically by dyspepsia, particularly the nervous form, irritability, depression of spirits, lassitude, and sometimes marked hypochondriasis. There may be in addition neuralgic pains and the general symptoms of neurasthenia. The local and general symptoms are probably dependent upon some disturbance of metabolism of which the oxaluria is one of the manifestations. It is a feature also in many gouty persons, and in the condition called lithaemia.