a. Etiology of Renal Calculi. The exact cause of kidney stones is unknown,
but predisposing factors include the following:
(1) Dehydration. Production of smaller amounts of urine promotes kidney
stones. Less liquid concentrates calculus-forming substances.
(2) Infection. Clumps of bacteria, particularly when stasis or obstruction
accompanies infection, can serve as a nucleus for calculus formation. Additionally,
infected and damaged tissue serves as a site for calculus development.
(3) Obstruction. Components of calculus can collect and adhere, forming
calculi (stones) in a patient with urinary stasis; for example, an immobile person with a
spinal cord injury. An obstruction also promotes infection with an even greater chance
of calculus formation.
(4) Metabolic factors. Certain metabolic factors may predispose the
formation of calculi. Included are hyperparathyroidism, renal tubular acidosis, elevated
uric acid (usually with gout), defective metabolism of oxalate, genetic defect in the
metabolism of cystine, and excessive intake of vitamin D or dietary calcium. Excessive
intake of milk and cheese products can result in too much dietary calcium.
b. Signs and Symptoms of Renal Calculi. The signs and symptoms vary with
the size, location, and cause of the calculi. Included are the following:
(1) Pain, the key symptom, will be excruciating and intermittent, usually
originating in the flank and radiating across the abdomen, and along the course of the
ureters into that area of the groin. A stone in the kidney will cause a dull ache in the
flanks with pain extending along the rib margin toward the umbilicus. A stone in the
ureter causes pain to radiate from the costovertebral angle down the course of the
ureter to the scrotum, or vulva to the inner thighs. A stone in the bladder causes pain to
radiate to the distal urethra. This pain accompanies micturition (urination).
Chills, fever, and frequent urination are common.
Hematuria, the discharge of red blood cells in the urine, is common.
(4) Pyuria, with or without bacteria, may be present. Pyuria is the presence
of pus in the urine.
(5) As a ureter stone is passed into the bladder, the patient will exhibit a
stab of pain followed by instant relief. If the stone is passed with urine, it is necessary to
attempt to retrieve it so that it may be analyzed.