FERGU

Hyponatremia - treat with water restriction, because it means that there is a water excess diluting the sodium. Important to treat to prevent brain swelling.

Edema - treat with salt restriction or diuretic, because it means that there is excess salt causing ECFV expansion.

ECFV is controlled by body sodium content.

Intracellular volume is controlled by sodium concentration. Exception is hyperglycemia, where glucose becomes an important osmole.

SIADH (pain, nausea, med side effects)

Hyperglycemia (which causes water movement from ICF compartment into ECF compartment, diluting the sodium)

Severe CHF, where ADH will be overactive

Afferent arteriolar dilation
Natriuresis

Low ECFV (CHF, cirrhosis) will stimulate PGI2 levels to rise to maintain renal perfusion.

Sodium regulation is stimulated by stretch receptors. Effectors of sodium regulation include:
-RAAS
-Prostaglandins
-Renal sympathetic nerves
-ANP
-Nitric oxide

Water regulation is stimulated by osmolarity in early stages. However, if the effective circulating volume drops to severe levels, then water reabsorption will be increased at the expense of osmolarity.
Effectors include:
-ADH

450 ml - 10 L/day

Cockcroft Gault equation

CrCl (ml/sec) = [(140 - age) * lean body wt] / (serum creatinine * 50)

► Multiply by 0.85 for women
► Multiply by 60 for ml/min
► Weight measured in kg, creatinine in µmol/L

• Anemia
• Bone disease (abnormal Ca2+ and PO₄ metabolism)
• Hypertension and CVD
• Malnutrition

FE(Na) < 1% → hypovolemia

FE(Na) > 2% → acute tubular necrosis

Transtubular Potassium Gradient

Interpretation:
□ In hyperkalemia, TTKG should be > 7 if tubules functioning normally
□ In hypokalemia, TTKG should be < 2 if tubules functioning normally

The most common: E. coli, Staphylococcus saprophyticus
Others:
Klebsiella pneumoniae
Proteus mirabilis
Group B Strep
Enterococcus

Lower UTI (cystitis):
□ Dysuria with turbid urine
□ Urgency
□ Frequency
□ Suprapubic pain
□ Hematuria
□ NO FEVER/CHILLS

Upper UTI (pyelonephritis)
□ Lower UTI symptoms (for 1-2 days)
□ Fever and chills
□ Flank pain

Collect no sooner than 2 hours after previous voiding.

Transported and processed in the laboratory within 2 hours
- If not, then the specimen should be refrigerated, transported on ice, and processed within 24 hours
- This is because certain bacteria can double every 20 mins at room temp.

Women sexually active
Diabetic women
Increase in prevalence with age
◊ 50% of women in long term care
◊ 40% of men in long term care
Impaired urinary voiding
Indwelling urinary devices (catheters)

12-16 weeks GA

Asymptomatic bacteriuria puts pregnant women at higher risk for
○ Pyelonephritis
○ Premature delivery
○ Infants of low birth weight

Pregnancy

Prior to urologic/gynecologic surgery
○ Treat with antibiotics the day before surgery, or just before surgery to ensure appropriate antibiotic levels at the time of the procedure

Surgery involving prosthetic material

Catheter removal in patients catheterized > 48 hours post surgery involving prosthetic material

3 or more episodes per year

DM
Symptoms of UTI for > 7 days
Age > 55
Pregnancy
Functional/anatomical/metabolic abnormalities of the urinary tract
Chronic catheterization

Quinolones (cipro)
- good for uncomplicated UTI (3 day therapy)
- good for complicated UTI (7 day therapy)
- expensive

Septra
- good for uncomplicated UTI (3 day therapy)
- inexpensive

Cefixime/Amoxicillin-clavulanate
- good alternative agent for children
- expensive
- side effect: diarrhea

Nitrofurantoin
- clinically equivalent to Septra
- 7 day course, 100 mg bid

• Potassium sparing
• Carbonic anhydrase inhibitors
• Loop
• Osmotic
• Thiazides

Inhibit CA, which in term inhibits reabsorption of H+ and HCO3-

Acetazolamide = carbonic anhydrase inhibitor.

Indications:
-glaucoma
-acute mountain sickness
-metabolic alkalosis

Side effects
- Metabolic acidosis
- Renal stones: alkaline urine causes calcium phosphate to precipitate
- Hypokalemia

Pharmacologic antagonists of aldosterone: spironolactone
MOA: antagonizes the mineralocorticoid receptor, preventing the transcription of ENaC on luminal membrane, and Na+/K+ on basolateral membrane.

Physiologic antagonists of aldosterone: triamterene and amiloride
MOA: antagonizes the ENaC on luminal membrane.

Adjunct for hypertension and CHF
□ Main purpose is to increase serum K⁺ levels, as other diuretics tend to cause hypokalemia

Primary hyperaldosteronism (spironolactone)

Hyperkalemia
□ Especially when combined with other agents that also increase K⁺ such as ACEi and ARBs
Metabolic acidosis
□ Reduced absorption of Na⁺ leads to reduced H⁺ excretion

Spironolactone specific: antagonism of androgen or progesterone receptors

Decreased Na⁺, K⁺, Cl⁻, Ca²⁺, Mg²⁺, H⁺

Since loop diuretics are highly plasma protein bound, they can't be filtered into the tubules. Instead, they rely on secretion into proximal tubules.

Compete with NSAIDs and probenecid for secretion in the proximal tubule.

Edema
Hypertension
Acute hypercalcemia

Loop diuretics

Furosemide

Decreased: Na⁺, Cl⁻, K⁺, H⁺

Increased: Ca²⁺

Thiazides used with anti-arrhythmics (quinidine, sotalol). Mechanism is unknown.

Hypertension (first-line)
Edema
Nephrogenic diabetes insipidus
Renal stones

Thiazides

Mechanism not confirmed, but likely due to ability to reduce intravascular volume, in turn stimulating Na⁺ reabsorption and reducing the amount of fluid presented to distal segments of nephron

Edema (diuresis): Oral: 25-100 mg/day in 1-2 doses; maximum: 200 mg/day

Hypertension: Oral: 12.5-50 mg/day

Increased intracranial pressure and cerebral edema

Increased intraocular pressure

Disequilibrium syndrome in dialysis

Acidosis: carbonic anhydrase inhibitors, and potassium-sparing diuretics

Alkalosis: loop and thiazide

Gout: loop, thiazide

Kidney stones: CAI (alkalinity),

Thiazides

Enhances reabsorption of calcium, and therefore reduces formation of calcium-containing renal stones

PHAROH
proteinuria
hypertension
azotemia (nitrogen in blood)
RBC casts
oliguria
hematuria

Group A Streptococcus, usually pharyngitis.

1-3 weeks after infection.

Autoimmune disease of kidneys and lung hemorrhage.
Anti-GBM antibodies, may cause RPGN.

(Mx: PACE - protein, albumin, cholesterol, edema)

Proteinuria (greater than 3.5 g/day), may be albumin only
Hypoalbuminemia
Edema
High serum cholesterol

< 150 mg/day

1.010 (dilute) - 1.030 (concentrated)

Minimal change disease - a disease of unknown etiology that causes effacement of foot processes of glomeruli.

Patients present abruptly with nephrotic syndrome
< 6 years old
No hematuria or hypertension
Responds to treatment with steroids
Not progressive

ASOT (antistreptolysin O titre) blood test

Focal glomerulosclerosis
-Renal disease
-HIV

Rapidly progressive glomerulonephritis
-Goodpasture syndrome
-Vasculitis
-Post-infectious

Post-infectious glomerulonephritis

Minimal change disease
-Unknown T-cell disorder

Diabetic glomerulosclerosis

Specific gravity
pH
Protein
Glucose
Ketones
Blood
Nitrite
Leukocyte esterase
Bilirubin
Urobilinogen

7.4

24 mmol/L

pH = 6.1 + log ([HCO₃⁻]/0.03*PaCO₂)

AG = Na⁺ - (Cl⁻ + HCO₃⁻)
Normal is 8-12 mEq/L
Calculated to identify the presence of significant unmeasured anions

Mx: MUDPILES
• Methanol
• Uremia
• Diabetic ketoacidosis
• Propylene glycol
• Isoniazid
• Lactic acidosis
• Ethylene glycol
• Salicylates

Diarrhea
Renal tubular acidosis

This is called hyperchloremic acidosis.

Osmolar gap = Measured osmolarity - 2 * [Na⁺] + [glucose] + [Urea] + [EtOH]

High OG identifies presence of uncharged osmols in serum (usually toxic alcohols)
□ Ethanol
□ Methanol
□ Ethylene glycol
□ Acetone
□ Isopropryl alcohol

Type 1 (distal)
□ Defective H⁺ secretion in distal tubule

Type 2 (proximal)
□ Impaired HCO₃⁻ reabsorption in proximal tubule

Type 4 (aldosterone deficiency/resistance)
□ Impairs H⁺ and K⁺ secretion
□ Patients become hyperkalemic
□ Impairs ammonium production

Note that there is no type 3 RTA

Vomiting, nasogastric suctioning, diuretic therapy.

a) Stabilize cardiac membrane
• Calcium gluconate

b) Use of agents that cause an intracellular shift of the potassium
• Insulin
• Sodium bicarbonate

c) Removal of potassium from the body
• Diuretics
• Na polystyrene sulfonate (kayexalate)
• Dialysis