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Category: Medical

Topic: The Renal System

Level: Paramedic

Next Unit: The Bladder and Urethra

12 minute read

The urinary tract is made up of:

  1. Kidneys, right and left.
  2. Ureters--which carry urine from the kidneys to the bladder.
  3. Bladder--which collects urine for excretion via contractions.

This is why an X-ray of the abdomen that includes the urinary tract is called a "KUB" film.


The Kidneys

The kidneys are paired organs located behind the peritoneum lining the abdominal cavity and are thus considered to be retroperitoneal organs. The left kidney is located slightly more superior than the right kidney due to the larger size of the liver on the right side of the body.

Both the vena cava lying to the right of the aorta and the size of the liver cause some distinctive features in the anatomy:

  • The right kidney is lower positioned relative to the left because of the bulk of the liver on the right side.
  • The left adrenal and ovarian/testicular veins empty into the left renal vein, which are closer for joining than the vena cava to the right.
  • The right renal artery is shorter than the left renal artery, which has to cross to the right-positioned vena cava.

ANTIDIURETIC HORMONE (ADH): The kidney's collecting ducts are normally impermeable to water, but in the presence of antidiuretic hormone (ADH) they become permeable to water and result in the reabsorption of water molecules. Dehydration will cause the release of higher levels of ADH, which in turn allows the kidneys to reabsorb more of the water passing through them into the bloodstream, thus attempting to normalize blood volume and pressure.



The kidneys have many roles in the body, they:

  • form urine
  • extract waste from the blood
  • balance body fluids
  • contribute to electrolyte balance
  • participate in blood pressure regulation
  • regulate pH
  • reabsorb/regenerate bicarbonate from urine
  • excrete hydrogen ions and fixed acids into the urine

Hormones that affect the kidneys include:

  • aldosterone
  • atrial natriuretic peptide (ANP)
  • antidiuretic hormone (ADH)
  • parathyroid hormone (PTH)


Emergencies Related to the Kidneys


PYELONEPHRITIS: Infection in the kidney can originate from generalized sepsis or via an obstruction below it that causes urine to back up into it. Also, a bladder infection, due to the continuity with the ureters and kidneys, can rise into either or both kidneys.

Pyelonephritis signs and symptoms include:

  • Fever
  • Back pain (unilateral/bilateral)--tender to tapping
  • Anemia
  • Malaise and possible neurological manifestations from electrolyte disturbances
  • Cloudy ("turbid") urine, possibly malodorous

The fevers from pyelonephritis can be spiking and high and are associated with increased red blood cell destruction causing anemia.


The continuity from kidneys to bladder depends on unhindered flow. If a stone (nephrolithiasis) were to lodge anywhere along this continuity, everything above will distend which causes severe pain (and in the case of the ureters, spasm) and make the areas of standing fluid collection inviting for pathogens.

The passage of urine goes from larger sites (collecting areas in the kidney) to narrower sites of passage (such as the ureters), where the narrowness is enough to prevent the passage of a stone farther down.

Signs and Symptoms from urinary tract obstruction include:

  • Flank pain, unless the "back-up" of urine has begun to swell the kidney--then you can add back pain as well.

The pain is sharp and incapacitating, coming in waves as the peristalsis of the ureteral spasms occurs. The point of maximum pain can travel down as the stone moves down the ureter.

  • Blood-tinged urine.


Initial kidney organ disease may result in a variety of clinical manifestations, ranging from asymptomatic hematuria to renal failure requiring dialysis. The gradual decline in function in patients with chronic kidney disease can progress, ultimately resulting in advanced disease that causes:

  • volume overload
  • hyperkalemia
  • metabolic acidosis
  • hypertension
  • anemia
  • mineral and bone disorders

End-stage renal disease results in signs and symptoms that are called UREMIA, these include:

  • anorexia
  • nausea, vomiting
  • pericarditis
  • peripheral neuropathy
  • central nervous system abnormalities (ranging from loss of concentration and lethargy to seizures, coma, and death)



Basically, the acute emergencies you are likely to encounter are systemic illness and pain complaints from pyelonephritis or sudden, incapacitating pain from a stone. Either way, transport is indicated with the maintenance of ABC (airway, breathing, and circulation), pain management, and other supportive care as indicated. In cases of a stone, IV hydration becomes necessary in hopes of flushing the stone out.

In cases of end-stage renal failure, you are transporting a primarily medical emergency, not a urinary tract emergency.