Exam 3 -- Renal Disease Flashcards
How long must there be a structural or functional kidney abnormality in order to consider the condtion as chronic?
3 months
True or false: less than 10% of US adults have some sort of chronic kidney disease (CKD)
False; greater than 10%
When would a condition be considered end stage renal disease (ESRD)?
When something extra is needed to keep the patient alive
True or false: African Americans are more likely to have ESRD than Caucasians
True; this may have some connection with uneven distribution of healthcare
What sorts of ocular symptoms may occur with renal disease?
Calcium deposits, lid edema, corneal changes, aniridia, cataracts, uveitis, optic nerve head edema, drusen around macula, retinal changes.
What are the three excretory functions of the kidney?
Removal of waste products, excretion of foreign substances (drugs, etc), regulate blood composition (amount of water, ion balance, acid-base balance)
True or false: the kidney has little, if any, endocrine function
False; it is involved with calcium regulation and uptake (calcitriol), RBC production (erythropoietin), autoregulation of blood flow and water reabsorption (prostaglandins, NO, and endothelins have one or both of these functions)
Of the blood received by the kidney, how much is actually filtered?
20%; the other 80% is for the kidney tissue itself and to transport the substances that are saved.
What is the flow rate of blood through the kidneys?
About 1.2 L/min
What is the name of the structure that connects the kidney to the bladder?
Ureter; it connects at the hilus
Which has a higher sodium concentration, the renal medulla or cortex?
Medulla
Where are juxtoglomerular cells located, and what is their function?
They are next to the glomerulus in the afferent arteriole; they are specialized smooth muscle cells that interact with baroreceptors to release renin in response to decrased blood pressure.
What characteristics of the glomerulus contribute to its filtration ability?
Fenestrated endothelium, incomplete basement membrane, podocytes with foot processes.
Know that the structure of the glomerulus is similar to the structure of choriocapilaris and the RPE cells, so things that affect the glomerulus could affect the eye too.
Free card
Where are the mesangial cells and what is their function?
They are between the glomerular capillaries and function to hold the capillaries together. They also play a phagocytic role and have contractile capabilities to control blood flow.
What happens to renal blood flow with sympathetic nervous system activation?
Afferent arteriole constricts and renin is released. Renin end result (through angiotensin II) is more vasoconstriction, especially of the efferent arteriole.
Which chemical mediators affect renal blood vessels?
Renin (indirectly through angiotensin II), prostaglandins, NO, endothelin
The glomerulus can be thought of as a negatively charged colander. What are the two main factors that characterize glomerulus selective permeability?
Size and charge (big things can’t fit through and negatively charged things are repelled)
Filtrate in the kidney is mainly composed of what?
Water, ions, glucose, amino acids, bicarbonate
True or false: the glomerulus plays a large role in reabsorption
False; it plays no role in reabsorption. It’s like when you clean out your dresser drawer; you just dump everything out onto the bed. Glomerulus just dumps stuff into the rest of the nephron, which then reabsorbs most of it.
The transport of many filtrate substances is related to reabsorption of which ion?
Sodium
What sorts of molecular transport are involved in reabsorption from the filtrate?
Exchange, shared transport, solvent drag
Which two characteristics are major modifiers of reabsorption?
Concentration of substances (there more there are, the more that can be reabsorbed), rate of flow (faster flow decreases time for transporter to get its job done)
What is the addition of substances into the filtrate called?
Secretion
Which substances are secreted in the proximal tubule?
Uric acid, organic acids
Which substances are reabsorbed in the proximal tubule?
Water, NaCl, bicarbonate, potassium, glucose, amino acids
Which substances are secreted in the descending loop of Henle?
None
Which substances are reabsorbed in the descending loop of Henle?
Water, due to hyperosmolarity
Which substances are secreted in the ascending loop of Henle?
None
Which substances are reabsorbed in the ascending loop of Henle?
NaCl and potassium, through active transport
Which substances are secreted in the distal tubule?
Potassium, hydrogen
Which substances are reabsorbed in the distal tubule?
Water, NaCl (increased by aldosterone), calcium (increased by PTH)
Which substances are secreted in the collecting duct?
Potassium (in exchange for NaCl reabsorption; increased by aldosterone)
Which substances are reabsorbed in the collecting duct?
Urea, water (increased by vasopressin), NaCl (in exchange for potassium secretion; increased by aldosterone)
In normal function, all of the ions and molecules of the filtrate experience some amount of reabsorption, except one. Which is it?
Creatinine
Where are the macula densa cells located, and what is their function?
They are located at the junction of the ascending loop of Henle with the distal tubule. Their function is to taste the filtrate to sense the concentration of NaCl. If [NaCl] is low, they tell the juxtaglomerular cells to release more renin so as to reabsorb more water.
The renin-angiotensin-aldosterone system acts to increase BP. As briefly as possible, outline this system.
Renin from kidney combines with angiotensinogen from liver to form angiotensin I, which is converted by ACE from lungs to angiotensin II. Angiotensin II increases thirst and causes vasoconstriction; it acts on the proximal tubule to increase sodium and water retention; it also acts on the pituitary to release vasopressin. Vasopressin acts on the kidney to increase water reabsorption. Pituitary also stimulates release of aldosterone from adrenal gland, which acts to increase sodium and water retention
What are the major stimulators for vasopressin release?
Decreased blood volume (sensed by baroreceptors in many places), increased blood osmolarity (primarily sodium and mannitol, but also glucose)
What stimulates erythropoietin release from the kidneys, and what effect does it have?
Hypoxia is the most common stimulant of erthyropoietin release; erythropoietin stimulates bone marrow production of RBCs
Calcitriol helps absorb calcium from the gut and is important for building bone. What molecule does it act on? What bone issue might a person with CKD have?
Calcitriol converts vitamin D to its metabolically active form (D3); CKD can cause osteoporosis
True or false: the kidneys can convert lactic acid to glucose
True.
What are the autocrine hormones or molecules that act in the kidneys?
Endothelins, NO, prostaglandins
The endothelins are peptides that are kidney autocrine hormones. What do endothelins do in the kidneys?
They increase BP through vasoconstrition and salt/water retention.
NO has autocrine functions in the kidneys. What does it do?
It causes more water to excreted; it is also involved in the macula densa feedback loop.
What is the overall effect of renal prostaglandins?
They increase renal bloodflow by preventing vasoconstriction; they also impair water reabsorption by blocking vasopressin in the collecting duct, prevent water and sodium reabsorption in the tubules, and prevent potassium excretion
Acute kidney failure can be brought about by which classes of common medications?
NSAIDs and steroids; these interfere with initial filtration, resulting in edema
The kidneys influence blood pH by excreting __________ when the blood is too acidic and ___________ when the blood is too basic.
Hydrogen ions; bicarbonate
How much (%) of the glomerular filtrate ends up becoming urine?
1%
What is the basis of the glomerular filtration rate test?
You have the patient ingest a known amount of a substance that they can’t get anywhere else, one that will be put into the filtrate by the glomerulus but not reabsorbed by the tubules, and take timed urine and blood samples to see how quickly this substance is eliminated from the body.
What is the basis of the creatinine clearance rate? What important use does this test have for optometrists (or any doctor)?
Have the patient collect their urine for 24 hours, then you draw their blood. Measure the creatinine in the urine and the creatinine in the blood to see how well the kidney is excreting the creatinine (none should be reasbsorbed). You would use this test to adjust a patient’s dosage of medications.
Serum creatinine is a useful screening test for kidney disease. If a person’s serum creatinine level is twice the normal value, what does this indicate about their kidney function?
2x the creatinine level means 50% kidney function (3x would mean 25%, and 4x would mean 12.5%, etc.)
The blood, urea, nitrogen (BUN) test is one that can be used to indicate kidney function. It measures levels of urea in the blood. Generally, how much urea should be reabsorbed, and how much should be excreted? A/An ______________ (increased/decreased) value of a BUN test compared to the normal would indicate reduced kidney function. What causes this value to change?
50% should be reabsorbed, 50% should be excreted. Increased BUN value would indicate reduced kidney function. This is because decreased glomerular filtration rate allows more reabsorption of urea.
What is azotemia?
An increase in BUN without symptoms.
What substances would you not expect to find in the urine of a healthy individual? What else could you use a urinalysis to look for?
You expect no protein, no blood, and no glucose. You could use urinalysis to look a patient’s pH (amount of dehydration) or look for presence of WBCs (possible infection)
The presence of which protein in the urine may be the first sign of kidney involvement in DM?
Albumin
What values tend to increase with kidney failure? Which tend to decrease?
Increase: serum potassium and phosphate; Decrease: serum calcium, pH, and bicarbonate
What is the NGAL test good for?
It is useful for detecting acute kidney damage so we can catch the issue earlier and have a better chance at fixing it. The other tests don’t catch damage until it is worse.
Which imaging technique involves a camera being worked up into the bladder?
Cytoscopy
Which imaging technique is the only one that can give an idea of kidney function, rather than only structure? What concern may there be with the contrast agent used?
Intravenous pyelogram (IVP); its contrast agent is related to iodine, so it can’t be used with patients allergic to iodine
What are the four categories of descriptors that can be used to describe a case of kidney disease?
Time (acute vs. chronic); structure affected (glomerular, tubular, etc); where issue is located (pre-renal, interstitial, post-renal); cause of issue (diabetic)
End stage renal disease (ESRD) is defined by kidney function reduced to ____________% of normal.
15
What is the most common cause of kidney failure? Second most common? What immune conditions may trigger kidney disease?
Diabetes is #1, HTN is #2; SLE, Sjogren’s, scleroderma can also cause kidney failure
True or false: symptoms of kidney disease tend to occur early on in the disease and always are acute
False; they tend to occur later on and can occur either acutely or slowly progressive
What are some of the common first symptoms of kidney disease?
High BP, swelling of legs, pulmonary edema, fatigue, HA, weight loss, N&V, itching (due to calcium and phosphate build up in tissues leading to drying), increased tendency to bleed (due to lower erythropoietin and therefore lower RBCs), cognitive impairment
Suppose a patient has azotemia. Once the patient has signs or symptoms (or we are able to identify the signs or symptoms), then call it what?
Uremia
What are some of the symptoms that CKD can cause in the blood?
Anemia (pallor, lethargy, breathlessness on exercise) and platelet abnormalities (epistaxis and bruising) due to low levels of erythropoietin
What are some of the symptoms that CKD can cause in the skin?
Pigmentation (due to MSH not being excreted as well) and pruritus (due to increased levels of calcium and phosphate drying out tissue)
What are some of the symptoms that CKD can cause in the GI tract?
Anorexia, N&V, diarrhea (due to acid-base imbalance and ion imbalance)
What are some of the symptoms that CKD can cause in the endocrine system?
Amenorrhea, erectile dysfunction, infertility (due to hormonal imbalance)
True or false: the tingling due to polyneuropathy in CKD extends only as far as the wrists and ankles
False; it extends up most of the arm/leg (stocking-glove pattern)
What are some of the symptoms that CKD can cause in the CNS?
Confusion, coma, seizures (due to ion imbalance in the blood)
What are some of the symptoms that CKD can cause in the cardiovascular system?
Pericarditis (due to ion imbalance), HTN, peripheral vascular disease, heart failure (due to fluid buildup)