Fluid & Electrolytes, Endocrine Disorders, Coagulation, Liver & Pancreas – Comprehensive Study Notes
Sodium–Water Balancing Basics
• Picture the vein as a tube whose lumen must always keep the ratio of water : Na⁺ roughly equal (normal serum Na⁺ 135-145\,\text{mEq/L}).
• "Fluid follows sodium" → wherever Na⁺ concentration is highest, water moves there to dilute it.
• Kidneys are the primary final-common-pathway regulators; every drop of blood passing the renal cortex is surveyed for Na⁺/water balance.
Practical bedside correlations
• Intake/Output (I&O) is nothing more than keeping water in = water out over a shift.
– Volume conversions: 1\,\text{oz}=30\,\text{mL}. Ex: 8 oz ⇒ 8×30=240\,\text{mL}.
• If a patient drinks 500 mL, the nurse expects ~500 mL urine later (allowing normal insensible losses).
Runner example (physiologic hypernatremia→hyponatremia)
Start of race – water = Na⁺, kidneys excrete normally.
1-mile mark – sweating removes water → vascular fluid becomes hypernatremic.
– Early sign: thirst. – Kidney response: ↓urine output; tissues donate water to plasma; hands/fingers swell.
– Nursing equivalent: encourage PO/IV fluids.Ignored thirst → body continues losing water; when total body water ↓60 % reserve, sweating & thirst stop → impending heat-stroke, seizures, death.
– End-stage picture = severe hyponatremia (Na⁺ finally falls because no extracellular water remains to mobilise).
Hospital hyper- vs hyponatremia
• Hypernatremia (water deficit)
– Causes: fever, GI loss, DI, prolonged exertion without rehydration.
– Body response: kidney water-sparring; cells dump water; brain cells shrink → seizure risk.
– Nursing: PO/IV free water, seizure precautions, monitor output.
• Hyponatremia (water excess)
– Causes: polydipsia, rapid free-water infusion, SIADH.
– Body response: kidneys dump urine; cells pull water → cerebral edema & seizures.
– Nursing: restrict fluids to prescribed amount, possible loop diuretic, seizure precautions.
• Key concept: Serum Na⁺ is a concentration problem. Adding/removing water—not sodium—moves the lab value.
Endocrine Block 1 – Adrenal Cortex (Cushing vs Addison)
Feature | Cushing (↑3 S’s) | Addison (↓3 S’s) |
|---|---|---|
Patho | ↑Cortisol/ steroids (tumor or chronic exogenous prednisone) | ↓Cortisol (autoimmune, gland destruction) |
3 S’s | ↑Steroids, ↑Sugar, ↑Sodium | ↓Steroids, ↓Sugar, ↓Sodium |
Body habitus | Moon-face, truncal obesity/ascites, buffalo hump, thin limbs, hirsutism | Thin frame, bronze hyperpigmentation |
Labs | Hyperglycemia 70-110→↑, hypernatremia, hypokalemia, hypocalcemia | Hypoglycemia, hyponatremia, hyperkalemia, hypercalcemia |
CV | Hypertension → stroke risk | Orthostatic hypotension |
Teaching | Low-Na⁺ diet, infection avoidance (immunosuppression), shoe/skin care (poor wound healing), Ca²⁺ & K⁺ supplements | Watch BP when standing, monitor K⁺ & Ca²⁺ |
ECG clue | Flat T-wave (low K⁺) | Peaked T-wave (high K⁺) |
Endocrine Block 2 – Posterior Pituitary (SIADH vs DI)
Parameter | SIADH (↑ADH) | DI (↓ADH) |
|---|---|---|
Urine volume | Scant “Dixie-cup” amounts | Polyuria (large volumes) |
Serum labs | Dilute → ↓Na⁺, ↓H/H, ↓serum osmolality | Concentrated → ↑Na⁺, ↑H/H, ↑serum osmolality |
Urine labs | Concentrated: ↑specific gravity >1.030, ↑Na⁺ | Dilute: ↓specific gravity <1.005, ↓Na⁺ |
BP trend | Hypertension (volume overload) | Hypotension (volume deficit) |
Nursing | Fluid restriction, hypertonic saline if severe, seizure precautions | Replace water (oral/IV), DDAVP, fall precautions |
Coagulation Case Study – Heparin / Warfarin / Liver
• Clotting factors are synthesized in the liver.
• Too MANY factors → pathologic thrombosis (family h/o). Too FEW → hemophilia.
Heparin drip (IV)
• Lab: aPTT ("cross the T’s → H for Heparin"), therapeutic 45-80\,\text{s}.
– If aPTT <45 → ↑rate per protocol. – If aPTT >80-90 → STOP infusion (do not merely decrease) and call provider; risk haemorrhage.
Warfarin (PO)
• Labs: PT 16-22\,\text{s} & INR 2-3 (therapeutic).
– Low INR → ↑dose; High INR → hold dose & vitamin K.
Hepatitis C Sequence & Portal Hypertension
• Blood products pre-1992 not screened → transfusion-related HCV.
• Chronic HCV → progressive hepatic fibrosis → cirrhosis (scarred, hard liver).
• Portal vein supplies all splanchnic blood to liver. Scar → resistance → \uparrow portal pressure.
– Back-pressure dilates collateral veins → esophageal varices, splenomegaly, ascites.
– Variceal hemorrhage = major death cause (patient story: fatal esophageal/GI bleed at home).
• Diagnostics
– Liver biopsy = gold standard but CONTRAINDICATED when coagulopathic (on heparin/warfarin).
– EGD visualises varices; can band/cauterize bleeders.
• Labs that track liver integrity: AST/ALT, bilirubin, albumin ↓, ammonia ↑, PT/INR ↑.
Ammonia & Hepatic Encephalopathy
• Protein → gut → ammonia (NH₃) absorbed → normally hepatocytes convert to urea → urine/stool.
• Cirrhosis ⇒ \uparrow NH₃ (normal 15-45\,µg/dL) → altered MS, "happy drunk." Tx:
– Lactulose PO or retention enema until 2-3 soft BMs/day.
– Rifaximin for bowel decontamination.
• Never give antimotility (e.g., loperamide) – they need to poop.
Albumin & Ascites
• Albumin normal 3.5-5\,\text{g/dL} binds water intravascularly.
• Hypoalbuminemia ⇒ third-spacing → abdominal ascites; paracentesis may ↓6 L at a time.
Pancreatitis High-Yield
• Pancreas = dual-function organ behind stomach.
– Endocrine: insulin/glucagon. – Exocrine: digestive enzymes.
• Acute pancreatitis = auto-digestion; extreme epigastric pain.
Management mnemonic "PANCREAS"
P – Pain control (opioid, PCA)
A – Aggressive IV fluids (prevent hypovolemia)
N – NPO STRICT + NG-suction PRN → stop pancreatic stimulation.
C – Calcium replacement if saponification.
R – Replace nutrition via TPN when >5-7 days NPO.
E – Enzymes (pancrelipase) once PO resumes.
A – Antibiotics ONLY for infected necrosis (example used: gentamicin).
S – Sugar monitoring (TPN → hyperglycemia); use sliding-scale insulin because pancreas is "on vacation".
TPN pearls
• Hyper-osmolar; rich in dextrose → EXPECT serum glucose elevation (e.g., >200\,\text{mg/dL}). Intervention: bolus/SSI insulin.
• Albumin can fall (3.2 g/dL) – expected, no immediate intervention until oral nutrition returns.
• Gentamicin risks: nephro- & oto-toxicity. Monitor BUN 10-20 & creatinine 0.6-1.3\,\text{mg/dL} before each dose; hold and notify MD if elevated.
• Weight gain of 1-2 kg in 24 h irrelevant unless HF/renal context.
Intake & Output Math (Guaranteed Exam Item)
• Liquids counted IN: anything liquid at room T° (water, milk, jello, popsicles, ice cream, soup). If it says "1 cup" use 240\,\text{mL} (no ½-ice rule).
• OUT: primarily urine; include emesis, drains if ordered.
• Bladder irrigation: subtract instilled volume from cath-bag total; NG irrigation is neutral (in = out immediately) → ignore. NG flush (stays in) is intake.
• Balance rule: If |IN – OUT| ≤ 300\,\text{mL} over 24 h → "balanced, continue to monitor".
– IN > OUT → consider fluid restriction/diuretic.
– OUT > IN → increase fluids, evaluate dehydration.
Quick Lab Ranges to Memorize (highlighted for first exam)
• Na⁺ 135-145\,\text{mEq/L}
• K⁺ 3.5-5.0\,\text{mEq/L}
• Ca²⁺ 9-11\,\text{mg/dL}
• Mg²⁺ 1.8-2.5\,\text{mEq/L}
• Albumin 3.5-5\,\text{g/dL}
• aPTT (heparin therapeutic) 45-80\,\text{s}
• PT 16-22\,\text{s} ; INR 2-3 (warfarin)
• Urine specific gravity 1.010-1.030
• Ammonia 15-45\,µg/dL
Organ Donation Perspective (Ethics/Patient-Family Care)
• Consent is more than a checkbox – each "yes" can save ≥5 lives (case story: 28-yo donor → maternal liver recipient, family bonded afterwards).
High-Yield Exam Triggers
• Anything about runner, marathon, sweating = think Na⁺/H₂O balance.
• Every sodium question really asks "water high or low?"
• First test’s very 1st question: TPN in pancreatitis – EXPECT hyperglycemia; intervene with insulin.
• Select-All-That-Apply exemplar (pancreatitis):
– High serum glucose (expected, needs SSI)
– Low albumin (expected, no action)
– Fever (expected infection sign → antipyretic/antibiotic)
– Elevated BUN/Cr on gentamicin → HOLD dose
– 1 kg weight gain alone ≠ priority unless HF/renal.
Prioritization reminder
• Who is most unstable / can deteriorate fastest (e.g., variceal bleed, cerebral edema seizure, potassium extremes) gets seen first.
• Medication first? Ask: Is it safe? Do labs/VS permit giving it? Do the critical thinking BEFORE choosing.
Bottom Line Clinical Links
• Sodium shifts = water shifts → brain injury if too fast/too far.
• "Opposites" trick works: Cushing vs Addison, SIADH vs DI.
• When a lab is out of range on a drip/medication, decide: increase, hold, or stop entirely (heparin >80 s → STOP, not titrate).
• Liver failure affects EVERYTHING: clotting, glucose, hormones, protein levels, drug metabolism.
• Protect yourself (gloves) – Hep C incubation up to 25 y; assume every drop is infectious.