Renal

How would the following affect the glomerular filtration rate (GFR) and net filtration pressure (NFP): (a) inflammation of the glomerular membrane, (b) constriction of the proximal convoluted tubule, and (c) hemorrhage?

(a) The NFP increases because of the increased presence of proteins in the glomerular filtrate. This causes an increase in the capsular oncotic pressure. As water follows the proteins, the decreased blood volume and pressure result in a decreased glomerular filtration rate. (b) A narrowed proximal convoluted tubule results in increased capsular hydrostatic pressure. As capsular hydrostatic pressure rises, glomerular filtration rate decreases. (c) As blood volume decreases, GFR and NFP decrease. The decreased blood volume ultimately decreases the blood pressure.

What are the common types of urinary calculus (kidney stones)?

-Calcium oxalate or calcium phosphate stones account for 70% to 80% of stones. -Struvite stones account for approximately 15% of urinary calculus and are made up of magnesium, ammonium, and phosphate. -Uric acid stones account for approximately 7% of stones. -Less common stone elements include cystine, 2,8-dihydroxyadeninuria, triamterene, indinavir, and ammonium acid urate.

Differentiate between the various types of urinary tract infections.

-Pyelonephritis is the term used to identify this type of involvement of the upper urinary tract. -Cystitis is inflammation of the bladder. -A urinary tract infection is inflammation of the urinary epithelium, followed by invasion and colonization by some pathogen. -Asymptomatic bacteriuria is bacteria in the urine that does not provoke infection.

What kinds of changes occur in the aging process in the renal system?

As a person ages, the kidneys slowly become smaller and the renal blood flow and GFR decrease. The actual number of nephrons decline and may be associated with oxidative stress and inflammation. The highest decrease in nephrons occurs between 40 and 80 years of age. The nephron itself also has degenerative changes such as atrophy of glomerular capillaries and a reduction in branching vessels. The glomeruli have been known to completely disappear. The specific gravity tends to be lower. Stressful conditions make it harder for the body to adapt. Hyperkalemia commonly occurs and glucose, bicarbonate, and sodium are not easily absorbed. Acid and base load response is slow and delayed. Crucial imbalances may occur due to sudden or massive changes in pH or fluid load, which can lead to hypervolemia or hypovolemia. The older adult may suffer from renal insufficiency due to acute losses or chronic fluid deficits. As the body ages, there is a decrease in the activation of vitamin D, which lowers the intestinal absorption of calcium. Neurogenic and myogenic changes in the bladder also occur.

Compare autoregulation, neural regulation, and hormonal regulation of renal blood flow.

Autoregulation is the locally mediated mechanism that tends to keep the rate of renal blood flow and GFR fairly constant when arterial pressures range from 80 to 180 mmHg. Thus it prevents wide fluctuations of arterial pressure from being transmitted to the glomerular capillaries. Autoregulation is accomplished through a local myogenic mechanism, which senses changes in arteriolar muscle stretch, and tubuloglomerular feedback, which senses changes in flow rate and sodium chloride reabsorption. Neural control is mediated by the sympathetic nervous system and results in arteriolar vasoconstriction when the system is activated. Sympathetic response is mediated reflexively through receptors in the carotid sinus and aortic arch. The major mechanism for hormonal regulation is the renin-angiotensin-aldosterone system, which can increase systemic arterial pressure and change renal blood flow. Release of renin can be inhibited by atrial natriuretic peptide, resulting in decreased blood pressure. Other hormones produced in the kidney may also affect renal blood flow; these include prostaglandins, urodilatin, endothelin, and kinins.

A woman has white blood cells present in her urinalysis results. How would you determine whether she has cystitis or pyelonephritis?

Cystitis is a bladder infection; pyelonephritis is a kidney infection. Both conditions demonstrate the presence of white blood cells and likely bacteria. One distinguishing factor for pyelonephritis is the presence of white blood cell casts. Casts originate in the renal tubules because of a decreased glomerular filtration rate. When white cells are also present in the tubules, they get caught in the protein matrix and form white blood cell casts. Because casts originate in the renal tubules and not in the bladder, they are not present in cystitis.

What is HSP?

Henoch-Schönlein purpura is also known as anaphylactoid purpura and exhibits hematuria, mild proteinuria, abdominal pain, and skin lesions.

intrarenal acute renal failure

Intrarenal acute renal failure is caused by impaired blood flow within the kidney. It is the result of direct damage to the kidney including ischemia or inflammatory damage. Examples of intrarenal causes include acute tubular necrosis (ATN), glomerulonephritis, malignant hypertension, disseminated intravascular coagulation (DIC), and renal vasculitis.

How can a person with chronic renal failure become anemic? How are they related?

Normocytic-normochromic anemia is a companion to chronic renal failure because of the insufficient production and release of erythropoietin, blood loss, and decreased red blood cell life span. Individuals will express common symptoms of anemia (e.g., dizziness, dyspnea, lethargy, pallor).

postrenal acute renal failure

Postrenal acute renal failure is caused by impaired outflow from the kidney. The passage of urine is blocked by an obstruction, causing urine to "back up" into the renal pelvis and altering pressures within the kidney. Examples are kidney stones, bladder outlet obstruction, and enlarged prostate.

prerenal acute renal failure

Prerenal acute renal failure is decreased renal function with elevated blood urea nitrogen (BUN) and plasma creatinine caused by impaired blood flow to the kidney. Blood flow and pressure reaching the afferent arteriole of the kidney are low, which causes a low glomerular filtration rate and eventual renal ischemia. Examples of prerenal acute renal failure causes include hypovolemia, hypotension, shock, hemorrhage, myocardial infarction with poor cardiac output, and left ventricular failure.

A man is suffering from stenosis of the left renal artery. The stenosis is reducing the blood flow to the affected kidney. Which of the pressures used to calculate the net filtration pressure is directly affected by this abnormality?

The blood flow to the left kidney is reduced. This change is reducing the blood hydrostatic pressure, thereby decreasing the glomerular filtration rate. The man compensates by releasing vasodilators to increase the diameter of the left renal artery as much as possible, and his right kidney, if functioning normally, will try to make up the difference.

While bathing her child, the mother discovers a firm, smooth mass on the child's flank. When touched, the mass is nontender. Otherwise, the child appears healthy and well. What type of mass does this child have and why?

The child has Wilms tumor, an embryonic, solid tumor of the kidney. The tumor is also known as nephroblastoma. It arises from undifferentiated embryonic renal tubule and glomerular cells called metanephric blastemal cells. The error in development occurs between weeks 8 and 34 in the fetus. However, the tumor does not grow until after birth. With Wilms tumor, the embryo-like cells grow in a rapid, undifferentiated manner. It may be associated with other congenital anomalies and may be metastatic.

A 3-year-old boy is admitted with primary nephrotic syndrome. What signs and symptoms would be identified? What is the primary treatment for this syndrome, and why?

The child would be lethargic, fatigued, and irritable. He would have generalized edema at night and dependent edema with protuberant abdomen during the day. The edema eventually progresses to excessive generalized edema with pulmonary congestion and genital swelling. He would have diarrhea, anorexia, malnutrition, and a decreased amount of frothy or foamy urine. His skin would be shiny and pale with hair changes. His blood pressure would be either normal or high. He would be more susceptible to infection. The primary treatment for nephrotic syndrome is the use of glucocorticoids (steroids) to decrease the inflammatory response.

What is the purpose of erythropoietin in the body?

The fetal liver and the adult kidney produce erythropoietin (EPO). It is responsible for normal erythropoiesis to occur. If tissue hypoxia occurs, erythropoiesis causes the bone marrow to produce red blood cells. Recombinant human erythropoietin (rH-EPO) is used to treat anemia of chronic renal failure and chemotherapy for cancer. It also affects endothelium and promotes angiogenesis, mitogenesis, and antiapoptosis.

normal renal blood flow

The kidneys receive 1000 to 1200 ml of blood per minute and 20% to 25% of CO. The GFR is related to renal blood flow, and autoregulation is found in renal blood flow.

Describe the different grades in vesicoureteral reflux (VUR).

VUR is when the ureters have a retrograde flow of bladder urine. This causes the infected urine from the bladder to be swept up to the kidneys. The grades are as follows: Grade I—reflux into a nondilated distal ureter Grade II—reflux into the upper collecting system without dilation Grade III—reflux into dilated ureter or blunting of calyceal fornices Grade IV—reflux into a grossly dilated ureter Grade V—massive reflux with ureteral dilation and tortuosity and effacement of the calyceal details; almost always happens with infant males