Hypokalemia - K+ 2.5 mEq/L

Immediate Priorities

1. Assess for emergency signs - muscle weakness, paralysis, ECG changes (U waves, T wave flattening, ST depression, QT prolongation)
2. Get an ECG now - AHA guidelines recommend cardiac monitoring in hypokalemia with prolonged QT interval
3. Check magnesium - hypomagnesemia causes refractory hypokalemia; must be corrected simultaneously

Clinical Workup

• < 15 mmol/day = extrarenal loss (GI losses, sweating, poor intake)
• > 15 mmol/day = renal wasting (diuretics, hyperaldosteronism, RTA, Bartter's, Gitelman's)

Treatment

Potassium Replacement

• Potassium phosphate - if concurrent phosphate deficit (e.g., DKA)
• Potassium bicarbonate/citrate - if concurrent metabolic acidosis

Route & Rate

• Recheck K+ 2 hours after end of infusion
• Use dextrose-free IV fluid - glucose triggers insulin release and can drop K+ further by 0.2-1.4 mmol/L
• Oral repletion can be surprisingly fast: 75 mmol oral K+ raises serum K+ by ~1.0-1.4 mmol/L in 60-90 min

Target Goals

Key Dangers at K+ 2.5

• Cardiac arrhythmias - risk is highest in elderly, organic heart disease, digoxin use
• Digoxin toxicity - hypokalemia enhances digoxin binding to cardiac Na+/K+-ATPase
• Rhabdomyolysis
• Diaphragmatic weakness / respiratory failure in severe cases
• Hepatic encephalopathy (increased renal ammoniagenesis)
• Insulin impairment - hypokalemia inhibits insulin release and worsens hyperglycemia

Refractory Hypokalemia?

Do Right Now

1. ECG Immediately

2. Check Magnesium (stat)

3. Potassium Replacement

Never exceed 10 mEq/h IV without continuous cardiac monitoring. Use normal saline as diluent - NOT dextrose (glucose spikes insulin and drops K+ further).

4. Recheck K+ in 2 Hours

5. Identify and Treat the Cause

• Review medications: diuretics, laxatives, steroids, amphotericin B, aminoglycosides
• Check urine K+ to distinguish renal vs. GI loss
• Consider aldosterone excess if hypertensive

Special Situations

Immediate Management

1. ECG (still recommended)

2. Potassium Replacement

• Use normal saline if IV - not dextrose
• Recheck K+ 2 hours after last dose
• If still < 3.5 on recheck, repeat the same dose

3. Check Magnesium

After Stabilization

• Find and treat the underlying cause (diuretics, poor intake, GI losses, etc.)
• Continue maintenance KCl (oral) if ongoing losses expected
• Dietary counseling: bananas, oranges, potatoes, spinach, beans

Target

Asymptomatic Hypokalemia - K+ 2.5 mEq/L

Step 1 - ECG

Step 2 - Check Magnesium

Step 3 - Potassium Replacement

• IV fluid: use normal saline, never dextrose
• Recheck K+ 2 hours after completion
• If K+ still < 3.5 on recheck → repeat dose

Step 4 - Find the Cause

Step 5 - Maintenance

Key point: Asymptomatic does not mean safe at 2.5 - treat promptly, recheck, and fix the root cause.

Next Steps After KCl Syrup

1. Recheck Potassium in 2 Hours

2. If K+ Still < 3.5 on Recheck

3. Check Magnesium Result

• If Mg2+ is low → replace magnesium sulfate simultaneously
• Without correcting Mg2+, K+ will keep dropping

4. Monitor for Any Emerging Symptoms

• Muscle weakness or cramps
• Palpitations
• Constipation / ileus

5. Identify and Treat the Underlying Cause

• Is the patient on diuretics? → Consider adding K+-sparing diuretic (spironolactone, amiloride) or KCl maintenance dose
• GI losses (vomiting/diarrhea)? → Treat the cause
• Poor dietary intake? → Dietary counseling

Summary So Far

Do not discharge until K+ is confirmed ≥ 3.5 on recheck.

NPO Guidelines Before MRCP Under GA

Regarding the Washroom

• MRCP itself does not require a full bladder (unlike pelvic ultrasound)
• Some centers ask the patient to void just before entering the MRI suite for comfort during the scan (MRCP can take 30-60 minutes)
• Under GA, a urinary catheter may be placed if the procedure is lengthy

Connecting to Your Patient (K+ 2.5)

• KCl syrup given orally - this counts toward the 6-hour light meal fasting window
• Confirm timing of KCl dose vs. scheduled procedure time
• Ensure K+ is rechecked and ≥ 3.5 before proceeding with GA - hypokalemia increases anesthetic risk (arrhythmias, prolonged neuromuscular blockade)

Bottom line: Patient can use the washroom anytime. Stop clear fluids 2h before GA, solid food/syrup 6h before. Confirm K+ is corrected before proceeding.

Immediate Assessment

First - How long since the procedure?

• < 6 hours post-GA with no urine → could still be expected (NPO + fasting effect)
• > 6 hours post-GA with no urine → urinary retention until proven otherwise

Check Bladder

Common Causes in This Patient

Management

Step 1 - Encourage Voiding (if bladder scan < 300 mL)

• Sit upright or stand if safe
• Run tap water nearby
• Warm water over perineum
• Adequate privacy and comfort

Step 2 - If Bladder Scan > 300-400 mL or Patient Uncomfortable

Step 3 - Fluid Status

• Check input vs. output balance
• Ensure adequate IV fluids running post-GA
• Resume oral fluids if awake and tolerating

Step 4 - Medications

• Tamsulosin 0.4 mg PO (alpha blocker) - if male patient with BPH component
• Bethanechol - rarely used, can stimulate detrusor
• Avoid further opioids if possible

Also Remember in This Patient

K+ was 2.5 - hypokalemia causes smooth muscle dysfunction including the detrusor. Correcting potassium may help restore normal bladder tone.

Red Flags - Escalate if:

• No urine output > 8 hours post-GA
• Bladder scan > 600 mL
• Rising creatinine / oliguria suggesting renal cause
• Patient in pain or hemodynamically unstable