Kidney Stones

Question 1

Pathophysiology

Answer 1

Crystals, when in supersaturated form, unite and form a stone

Stones:

1. Calcium oxalate – most common form of renal calculi
2. Calcium phosphate
3. Uric acid
4. Struvite (magnesium ammonium phosphate) – UTI
5. Cystine

Question 2

Clinical manifestations

Answer 2

1. Quick onset of severe pain
2. Pain in flank, back, or lower abdomen
3. Excruciating
4. Renal colic – sharp, severe pain due to stretching/dilation/spasm of the ureter in response to the stone
5. N/V/
6. Groin pain
7. May manifest with UTI – fever, pain, chills
8. Hard time sitting still

Question 3

Factors involved

Answer 3

Factors:
1. pH – High pH = Less soluble calcium and phosphate; Low pH = Less soluble uric acid and cystine

2. Solute load – low fluid intake
3. FHX
4. Conditions with enhanced enteric oxalate absorption (i.e. gastric bypass) – calcium oxalate stones
5. Conditions with acidic uric acid precipitation – constant D/, gout, DM, insulin resistance, obesity
6. Dietary factors – low intake of fluid, calcium, potassium; high intake of oxalate, sodium, sucrose, fructose, and animal protein

Question 4

Diagnostics

Answer 4

Tests:
1. CT/KUB – non-contrast spiral CT (kidneys, ureter, bladder)

2. Ultrasound
3. Intravenous pyelogram (IVP) – dye to evaluate kidneys, ureter, bladder
4. Complete urinalysis
5. Chem panel – calcium, phosphorus, sodium, potassium, bicarb., uric acid, BUN, Cr.
6. Recurrent stone formers – 24 hr. urine (measuring calcium, phosphorus, magnesium, sodium, oxalate, sulfate, potassium, uric acid, and total volume)

Question 5

Medical management

Answer 5

Geared at prevention of new stone formation and passage of stone

Approaches:
1. Acute event (hope passage) – manage acute attack by forcing fluid, managing pain, infection, and obstruction (stones <4mm pass on own; weeks)

2. Evaluation of cause – History, nutrition (vitamin, fluid intake), exercise, history of illness (especially GI, GU)
3. Nutritional therapy based on stone – Calcium (milk, dried fruits, nuts, beans); Oxalate (dark roughage, spinach, asparagus, cabbage, chocolate, tea); Purine (sardines, herring, mussels, liver, kidney, meat soups, bacon)
4. Invasive – procedural and/or surgery

Question 6

Lithotripsy

Answer 6

Extracorporeal shock wave (medical management) – common (45min-1 hr.)

Sound waves used to break stones into tiny pieces; cauterization before/after procedure to eliminate stones

May use general anesthesia, and pain medication prior to procedure

PRE-OP – NPO

POST-OP:

1. Recovery room (2 hrs.)
2. Monitor for hematuria – force fluids, prevent infection
3. Stent may be left – removed after 2 weeks
4. Surgery – nephrolithotomy, possible nephrectomy

Question 7

Nursing management

Answer 7

Asses:
1. I&Os

2. Nutritional history
3. FHX
4. Pain
5. Urinalysis – RBCs, WBCs, bacteria
6. 24 hr. urine – Increased uric acid, calcium, phosphorus, oxalate, or cystine
7. Labs – recurrent stones can cause kidney damage and possible loss of function (BUN, Cr., calcium, uric acid, WBCs)
8. 2L fluid intake/day (3L for active pts)
9. Reduce risk factors – manage diet (limit purines if uric acid stones), facilitate urination, manage pain, monitor labs, look for signs of infection
10. Care coordination – dietary consult (pt history, high risk foods, sample diet)

Question 8

Pt education

Answer 8

Promote:
1. >2L/day or 3L/day (active pt) fluid intake

2. Ambulation to promote excretion of stone
3. Strain urine
4. Monitor diet to prevent future stones
5. Education of dietary items to avoid