Kidney Stones and Kidney Abnormalities

Question 1

How do kidney stones form from urine?

Answer 1

1. The urine is too concentrated, due to an increase in the solute or due to a decrease in the solvent.
2. The urine becomes supersaturated and solute precipitates.
3. The solute precipitates forming crystals that act as nidus.

Question 2

Nidus

Answer 2

A place where more solutes can deposit, over time this builds up a crystaline structure.

Question 3

What substances inhibit crystal growth and aggregation?

Answer 3

Magnesium and citrate

Question 4

What substance is most commonly responsible for forming kidney stones?

Answer 4

Calcium oxalate

Question 5

What are the different types of kidney stones?

Answer 5

Calcium oxalate stones
Calcium phosphate stones
Uric acid stones
Struvite stones
Cystine stones
Xanthine stones

Question 6

Outline calcium oxalate crystals.

Answer 6

Dark brown crystal.
Radiopaque.
More likely to form in acidic urine.

Question 7

Outline calcium phosphate crystals.

Answer 7

Dirty white crystal.
Radiopaque.
More likely to form in alkaline urine.

Question 8

What are risk factors for calcium based kidney stones?

Answer 8

Hypercalcemia
Hypercalciuria
Hyperoxaluria

Question 9

Outline uric acid stones.

Answer 9

Red brown stone.

Radiolucent (transparent to X-rays).

Question 10

What are risk factors for uric acid stones?

Answer 10

High levels of uric acid are linked to consuming lots of purine - consumption of purine rich foods.

Question 11

Purine rich foods:

Answer 11

Shellfish
Red meat
Anchovies
Organ meat

Question 12

High levels of uric acid in the blood can cause kidney stones and what other condition?

Answer 12

Gouty arthritis - especially in the first metatarsal joint (big toe).

Question 13

Outline struvite stones.

Answer 13

Termed infection stones and are a mix of Mg2+, ammonium, phosphate.
“Staghorn stones”.
Dirty white.
Radiopaque.

Question 14

How can bacterial infection lead to the development of struvite stones?

Answer 14

Bacteria like Proteus mirabilis, Proteus vulgaris, and Morganella morganii use the enzyme, urease, to split urea into ammonia and carbon dioxide.
The ammonia makes the urine more alkaline and favors precipitation of magnesium, ammonium, and phosphate into struvite stones.

Question 15

Why are struvite stones termed staghorn stones?

Answer 15

Because they often branch into the several of the renal calyces and look like the horns of a staghorn deer.

Question 16

What are risk factors of developing struvite stones?

Answer 16

UTI’s
Vesicoureteral reflux
Obstructive uropathies

Question 17

Outline cystine stones.

Answer 17

Yellow / light pink stone.

Radiopaque on X-ray.

Question 18

Outline xanthine stones.

Answer 18

Red brown in colour.

Radiolucent.

Question 19

What are the general symptoms of kidney stones?

Answer 19

Dull or localised flank pain in the mid to lower back.
Renal colic - sharp constant pain.
Haematuria.

Question 20

What causes the renal colic pain in kidney stones?

Answer 20

Dilation, stretching and spasm due to obstruction of the ureter - subsides when the stone gets to the bladder.

Question 21

Where are the three most common places for a kidney stone to be lodged?

Answer 21

1. Pelviureteric junction.
2. Pelvic brim.
3. Vesicoureteric junction - where the ureters enter the bladder.

Question 22

How are kidney stones diagnosed?

Answer 22

History
Physical examination
Imaging
Urinalysis

Question 23

What is the treatment for kidney stones?

Answer 23

Hydration to reverse the process of precipitation.
Medications for: Pain, reduce stone formation and alpha adrenergic blockers to help the stone pass through.
Shockwave lithotripsy - sound waves to break up the stones.
Surgery.

Question 24

Nephrolithiasis

Answer 24

The formation of kidney stones.

Question 25

The kidneys develop from what germ layer?

Answer 25

Mesoderm

Question 26

Renal agenesis.

Answer 26

Renal agenesis is a condition in which a newborn is missing one or both kidneys.

Question 27

Summarise unilateral Renal agenesis.

Answer 27

Unilateral renal agenesis (URA) is the absence of one kidney.
Usually have some compensatory hypertrophy in
other kidney - good prognosis.

Question 28

Summarise bilateral renal agenesis.

Answer 28

Bilateral renal agenesis (BRA) is the absence of both kidneys.
Fatal, 40% still-born and remainder die shortly after birth.
Lack of fetal urine – oligohydramnios.

Question 29

Potter syndrome

Answer 29

Potter syndrome - The fetus has bilaterally absent kidney this results in associated pulmonary hypoplasia of a neonate as a direct result of oligohydramnios and compression while in utero.

Question 30

Renal dysplasia

Answer 30

General renal malformation - incomplete branched ducts, undifferentiated renal mesenchyme, small, may contain multiple cysts, ureter may contain non-patent section.

Question 31

Ectopic kidney

Answer 31

An ectopic kidney is a birth defect in which a kidney is located in an abnormal position.

Question 32

What complications can arise with ectopic kidney?

Answer 32

Often no problems however can result in urinary problems, such as urine blockage, infection, or urinary stones.

Question 33

Horseshoe kidney

Answer 33

With horseshoe kidney, as the kidneys of the fetus rise from the pelvic area, they become attached (“fuse”) together at the lower end or base.

Question 34

Multicystic dysplastic kidney (MCDK)

Answer 34

Arises in fetal development, the kidney consists of irregular cysts of varying sizes. Multicystic dysplastic kidney is a common type of renal cystic disease, and it is a cause of an abdominal mass in infants.

Question 35

Polycystic kidney disease.

Answer 35

Polycystic kidney disease (PKD) is an inherited disorder in which clusters of cysts develop primarily within your kidneys, causing your kidneys to enlarge and lose function over time. Cysts are noncancerous round sacs containing fluid. The cysts vary in size, and they can grow very large.

Question 36

What are ADPKD and ARPKD?

Answer 36

Autosomal dominant polycystic kidney disease

Autosomal recessive polycystic kidney disease

Question 37

What is the difference between ADPKD and ARPKD?

Answer 37

ADPKD causes cysts to form only in the kidneys and symptoms of the disease may not appear until a person is between 30 and 50 years old. Autosomal recessive PKD (ARPKD) is a much less common form of PKD. ARPKD causes cysts to form in both the kidneys and the liver.

Question 38

Duplicated ureter.

Answer 38

Duplicated ureter or Duplex Collecting System is a congenital condition in which the ureteric bud, the embryological origin of the ureter, splits (or arises twice), resulting in two ureters draining a single kidney. It is the most common renal abnormality, occurring in approximately 1% of the population.

Question 39

Common causes of hypercalcaemia leading to stone formation are:

Answer 39

Primary hyperparathyroidism
Sarcoidosis
Vitamin D ingestion

Question 40

Read this summary of Autosomal recessive polycystic renal disease:

Answer 40

Infantile disease is inherited as an autosomal recessive and presents within the first 9 months of life with gross abdominal distension because of renal masses. The child is pale, has easily palpable kidneys and renal failure. Most infantile polycystic disease has a hopeless prognosis and, without dialysis or transplantation death takes place before the age of 18 months.

Question 41

Polycythaemia

Answer 41

High concentration of red blood cells in your blood.

This makes the blood thicker and less able to travel through blood vessels and organs.

Question 42

What are the clinical features of cystic kidneys?

Answer 42

▪ Loin pain from increase in size of the kidneys.
▪ Acute loin pain with haematuria because of haemorrhage into the cysts.
▪ Hypertension and its associated sequelae.