Approach to hyperkalemia
A case of type IV renal tubular acidosis
Lê Vĩnh Nghi, MD
Internal Medicine Resident
VinUniversity GME Program
The 24th National Scientific Congress of Vietnam Association of Critical Care Medicine, Emergency and Clinical Toxicology
Renal physiology + Renal tubular acidosis
Normal tubules
Proximal: Absorb Bicarbonate (2)
Distal: Excrete Hydrogen (1)
Collecting: Aldosterone effect (4)
2
05/04/2024
RTA: CAN’T DO
Proximal: 2: Absorb Bicarbonate (HCO3-)
Distal: 1: Excrete Hydrogen (H+)
Collecting: 4: No Aldo or No Aldo effect → Hyperkalemia
Pearls: Renal tubular acidosis
Main cause: diabetic nephropathy → ↓renin ↓aldo
3
05/04/2024
Bello CHPRT et al. Diabetes mellitus and hyperkalemic renal tubular acidosis: case reports and literature review. J Bras Nefrol. 2017
Case report: Clinical characteristic
74-year-old male, history: hypertension, type 2 diabetes mellitus, prior ischemic stroke, chronic kidney disease
Presents with hyperkalemia
For 6 months, he has been bedridden due to the stroke, eyes open, slow response, no talking. Nutrition through nasogastric catheter.
Monthly lab tests (CBC, CMP) at home
Meds: Valsartan, Amlodipine, Dapagliflozin, Rosuvastatin (long time)
4
05/04/2024
Case report: Clinical characteristic
History of present illness
Occasional lab test: K = 6.0. Turbid yellow urine 1200ml/day
No other symptoms (fever, nausea, vomiting, chest pain, shortness of breath, abdominal pain)
Physical examination: HR 80, BP 140/90, T 37, RR 15, W 50kg
Eyes open, slow response, no talking, not in pain distress, no edema
Normal heart and lung sounds, non-tender abdomen, no bladder distention, (R) weakness, turbid yellow urine on Foley catheter
5
05/04/2024
Labs results
Complete blood count, ECG: normal
6
05/04/2024
Comprehensive metabolic panel | Results |
Glucose (mmol/L) | 8.0 |
Urea (mmol/L) | 9.5 |
Creatinine (umol/L) | 140 (1.58 mg/dL) |
eGFR (ml/min/1.73m2) | 45 |
Na+ (mmol/L) | 128 |
K+ (mmol/L) | 6.0 |
Cl- (mmol/L) | 100 |
Serum osmolality | 273.5 |
pH | 7.29 |
pCO2 | 23 |
HCO3- (mmol/L) | 14 |
Lactate (mmol/L) | 0.7 |
Anion gap | 12 (normal) |
Urine biochemistry | Results |
pH | 5.0 |
Leucocyte | 500 |
Blood | (-) |
Glucose | (-) |
Albumin (mg/L) | 80 |
Na+ (mmol/L) | 60 |
K+ (mmol/L) | 14.51 |
Cl- (mmol/L) | 55 |
Creatinine (mmol/L) | 2.076 |
Estimated urine osmolality (mmol/kg) | 350 |
Labs interpretation
Non anion gap metabolic acidosis (NAGMA)
Hyperkalemia
Suspected bacteruria
7
05/04/2024
K+ homeostasis: Do the kidneys work well ?
Urine K excretion measurement
8
05/04/2024
| |
TTKG | 2 (< 7) |
14.51 * 273.5
350 * 6.0
=
TTKG: low K excretion, suggesting hypoaldosteronism
Hyperkalemia: Subsequent lab results
9
05/04/2024
Serum biochemistry (lying flat) | Results |
Aldosterone (pg/mL) | 7.0 (low) (12.0 – 157.50) |
Renin (uIU/mL) | 2.0 (low) (2.8 – 39.9) |
Hyperkalemia approach
10
05/04/2024
Non anion gap metabolic acidosis approach
11
05/04/2024
First Aid for the USMLE Step 2 CK 10e: Renal
Renal tubular acidosis: Treatment
Correction of chronic acidemia
Type 1: Acid secretion impairment, treat with Alkali
Type 2: Bicarbonate wasting, treat with Base (alkali)
Type 4: ALDOsterone disorder, treat with 4semide
12
05/04/2024
Patient’s treatment & progression
The patient was treated with potassium-lowering regimen:
Insulin – Glucose – Bicarbonate – Kayexalate – Furosemide
After, serum K+ 3,7 – 4.5, fully responded metabolic acidosis
→ Serum K+ responded to Furosemide therapy
Discharge after a week
13
05/04/2024
Renal tubular acidosis: Summary
14
05/04/2024
Look for the cause