Fluids and Electrolytes
A 22-year-old woman participating in a marathon is evaluated in the medical tent for headache, confusion, and disorientation after she stopped running at mile 20. This is her first marathon. On physical examination, temperature is 100.4F, BP is 110/72, HR 110min, and RR is 20/min. The patient is confused. The remainder of the examination is normal. Laboratory studies show a serum sodium level of 130 mEq/L. What is the most appropriate management?
100-mL bolus of 3% saline
A 23-year-old woman is evaluated for a 1-week history of muscle weakness. Medical history is significant for chronic migraine headaches. Medications are topiramate, sumatriptan, naproxen, and aspirin. Vitals are normal. BMI is 19. Exam is normal.
Labs: Sodium 142 mEq/L, Potassium 3.1 mEq/L, Chloride 120 mEq/L, Bicarbonate 15 mEq/L, Urine sodium 18 mEq/L, Urine potassium 8.0 mEq/L, Urine chloride 32 mEq/L.
What is the most likely cause of this patient's metabolic acidosis?
Surreptitious laxative use
Normal anion gap metabolic acidosis can be caused by GI bicarbonate loss, renal loss of bicarbonate, or the inability of the kidney to excrete acid. A negative urine anion gap suggests appropriate kidney excretion of acid and therefore GI bicarbonate loss as the cause of normal anion gap metabolic acidosis.
A 23-year-old woman is evaluated during a follow-up visit for focal segmental glomerulosclerosis that was diagnosed 3 weeks ago. The edema in her lower extremities has not improved on her current regimen of prednisone, losartan, atorvastatin, and maximal doses of oral furosemide. Vitals are normal. The patient weighs 72 kg (158.7 lb). There is a 3-mm pitting edema of the lower extremities through the mid-thigh, equal on both sides. The remainder of the examination is unremarkable. CT of the chest is normal.
Labs: Albumin 2.0 g/dL, Total cholesterol 303 mg/dL, Creatinine 0.6 mg/dL, Urine protein-creatinine ratio 9150 mg/g.
What is the most appropriate management?
Add a thiazide diuretic and/or potassium-sparing diuretic
A 45-year-old man is evaluated in the emergency department for painful myalgia of his legs and difficulty walking after running in a 10-kilometer race. Since the race, he has had minimal output of dark brown urine. He has hyperlipidemia treated with high-intensity atorvastatin. On physical examination, temperature is 37.7 °C (99.9 °F), blood pressure is 112/67 mm Hg, and pulse rate is 88/min. Mucosae are dry, and skin turgor is diminished. The muscles of the upper and lower extremities are tender to palpation. The remainder of the examination is normal.
Labs: Calcium 7.5 mg/dL, Creatinine kinase 57,000 U/L, Creatinine 1.5 mg/dL, Sodium 137 mEq/L, Potassium 5.3 mEq/L, Chloride 104 mEq/L, Bicarbonate 19 mEq/L, Phosphorus 6.3 mg/dL, Urate 9.4 mg/dL, Urinalysis: specific gravity 1.012, pH 5.5, 3+ blood, trace protein, 1-2 erythrocytes/hpf and pigmented granualar casts/hpf
What is the most likely cause of the patient's findings?
Rhabdomyolysis
Acute tubular necrosis due to rhabdomyolysis.
A 54-year-old man is evaluated during a new patient visit. He has a 30-year history of type 2 diabetes mellitus and 10-year history of hypertension. Medical history is also significant for obesity and hypercholesterolemia. Medications are amlodipine, atorvastatin, canagliflozin, metformin, and lisinopril-hydrochlorothiazide. At his last visit to his previous physician, serum creatinine level was 1.4 mg/dL (123.8 µmol/L), and estimated glomerular filtration rate was 58 mL/min/1.73 m2. On physical examination, blood pressure is 158/82 mm Hg, and pulse rate is 62/min; other vital signs are normal. BMI is 38. The remainder of the examination is normal.
Labs: Albumin 3.5 g/dL, Creatinine 1.6 mg/dL, Electrolytes normal, eGFR 50, Urinalysis no blood and 2+ protein.
Results of kidney ultrasonography and referral to an ophthalmologist for a dilated retinal examination are pending.
What is the most appropriate test to assess the prognosis of this patient's chronic kidney disease?
Spot urine albumin-creatinine ratio
In patients with chronic kidney disease, albuminuria is associated with increased renal and cardiovascular morbidity and mortality.
A 38-year-old woman seeks treatment for polyuria and nocturia that began 6 weeks ago after starting lithium for bipolar disorder. Medical history is otherwise unremarkable. Her only other medication is olanzapine. Physical/vitals are normal. Labs showed sodium of 145 mEq/L and urine osmolality of 200 mOsm/kg H2O.
What is the most appropriate management?
Add amiloride
Treatment of lithium-induced arginine vasopressin resistance (nephrogenic diabetes insipidus) is best accomplished with amiloride, as it blocks the epithelial sodium channel in the collecting tubule and prevents the uptake of lithium by these cells. If ineffective, limit solute intake and cause mild volume depletion with the use of a thiazide diuretic.
A 55-year-old man is evaluated for a 4-month history of persistent hyperkalemia and intermittent diarrhea. Medical history is significant for long-standing type 2 diabetes mellitus and hypertension. Medications are metformin, atorvastatin, atenolol, and amlodipine. Physical and vitals are normal.
Labs: Sodium 138 mEq/L, Potassium 5.3 mEq/L, Chloride 112 mEq/L, Bicarbonate 18 mEq/L, eGFR 56 mL/min/1.73 m2, Urinalysis: specific gravity 1.020, pH 5.0, no blood, no leukocytes, no ketones; Urine sodium 45 mEq/L, Urine potassium 10 mEq/L, Urine chloride 40 mEq/L.
What is the most likely cause of this patient's hyperkalemia?
Type 4 (hyperkalemic distal) renal tubular acidosis
Diabetes mellitus is a common cause of type 4 RTA characterized by hyperkalemia, a normal anion gap metabolic acidosis, and a urine pH <5.5. Drug-induced type 4 RTA can be caused by ACE inhibitors, ARBs, heparin, and NSAIDs.
A 38-year-old man is evaluated during a follow-up visit for proteinuric chronic kidney disease. Family history is significant for end-stage kidney disease in two uncles and a female cousin. He has no other medical problems, and his only medication is lisinopril. The patient is of African descent. Vital signs are normal. There are features of generalized anasarca, with marked edema of the lower extremities.
Labs: Albumin 2.2 g/dL, Total cholesterol 264 mg/dL, Creatinine 1.8 mg/dL, Urinalysis showed no blood and 4+ protein, Urine protein-creatinine ratio is 7850 mg/g.
What is the most likely diagnosis?
Focal segmental glomerulosclerosis
Most common form of the nephrotic syndrome in patients of African descent, likely mediated in part by variants in the APOL1 gene.
A 62-year-old man is evaluated in the emergency department for increasing abdominal and bilateral flank pain. The pain began yesterday, 2 days after he took primaquine prescribed as antimalarial prophylaxis for planned travel. On physical examination, temperature is 38.1 °C (100.6 °F), blood pressure is 102/55 mm Hg, pulse rate is 110/min, and respiration rate is 22/min. Cardiac examination reveals tachycardia without extra sounds. There is no edema. The remainder of the examination is unremarkable.
Labs: Haptoglobin 10 mg/dL, Hemoglobin 7.9 g/dL, Reticulocyte count 8%, Total bilirubin 5.8 mg/dL, Blood urea nitrogen 32 mg/dL, Creatinine 1.9 mg/dL, Lactate dehydrogenase 1250 U/L, Urinalysis: Specific gravity 1.010, pH 5.0, 3+ heme, 1+ albumin, no erythrocytes, leukocytes, or leukocyte esterase, numerous pigmented granular casts.
Examination of the peripheral blood smear shows bite cells.
What is the most likely diagnosis?
Heme pigment nephropathy
Myoglobin and hemoglobin are heme pigment-containing proteins that can cause acute kidney injury. Heme pigment nephropathy is associated with a positive urine dipstick for blood in the absence of erythrocytes and the presence of pigmented granular casts.
A 58-year-old woman is evaluated during a follow-up visit for progressive stage G3 chronic kidney disease. Her average blood pressure using home blood pressure monitoring is 130/70 mm Hg. She walks three times weekly for exercise. Medical history is also significant for hypertension. Medications are chlorthalidone, cholecalciferol, furosemide, losartan, and metoprolol. On physical examination, vital signs are normal. There is no jugular venous distension. Lungs are clear to auscultation. There is trace bilateral leg edema.
Labs: Total cholesterol 178 mg/dL, Creatinine 1.5 mg/dL, eGFR 44, Urine albumin-creatinine ratio 420 mg/g.
What is the most likely expected cause of premature death in this patient?
Cardiovascular disease
Leading cause of death among patients with CKD. Management should address cardiovascular risk factors, such as blood pressure control, glycemic control, and treatment of hyperlipidemia.
A 46-year-old woman is evaluated during a follow-up visit for hypertension, T2DM, and stage G3 CKD. She reports no symptoms. Medications are losartan, amlodipine, metformin, canagliflozin, and rosuvastatin. BP is 124/72. Other vitals/exam are normal.
Creatinine 1.6 mg/dL, Sodium 136 mEq/L, Potassium 5.6 mEq/L, Chloride 104 mEq/L, Bicarbonate 24 mEq/L, Urine albumin-creatinine ratio 320 mg/g.
ECG is normal. The patient is counseled to start a low potassium diet. What is the most appropriate management?
Add a potassium binders.
Potassium binders such as patiromer and sodium zirconium cyclosilicate can be used to treat hyperkalemia in patients with chronic kidney disease.
A 52-year-old woman is evaluated for abdominal pain. She had been drinking alcohol for one week and had episodes of nausea, vomiting, and abdominal pain over the past 24-48 hours. She was hospitalized 1 year ago with isopropyl alcohol intoxication. She reports no other medical problems and takes no medications. BP 110/72, HR 110/min, RR 20/min. BMI is 18. Abdomen is diffusely tender to palpation.
Labs: BUN 32 mg/dL, Sodium 139 mEq/L, Potassium 3.9 mEq/L, Chloride 100mEq/L, Bicarbonate 11 mEq/L, Ethanol 40 mg/dL, Glucose 72 mg/dL, Plasma osmolality 290 mOsm/kg H2O, Urinalysis: specific gravity 1.030, pH 5.5, no blood, trace ketones.
What is the most likely diagnosis?
Alcoholic ketoacidosis
Results in an increased anion gap metabolic acidosis and minimal ketones on urine dipstick analysis. Ethylene glycol, methanol, and isopropyl alcohol toxicities are associated with an increased osmolal gap.
A 69-year-old man is evaluated for a 4-week history of lower extremity edema. He has a 45-pack-year history of smoking but quit 3 years ago. A screening colonoscopy performed 1 year ago was normal. He has no other medical history and takes no medications. Vitals are normal. There is a 2-mm pitting edema of the lower extremities through the ankles, equal on both sides.
Labs: Albumin 2.9 g/dL, Total cholesterol 311 mg/dL, Creatinine 1.0 mg/dL, 24-hour urine protein excretion 6300 mg/24 h.
Kidney biopsy shows membranous nephropathy with negative staining for the phospholipase A2 receptor angigen.
What is the most appropriate test to perform next?
Noncontrast CT of the chest
The initial step in the management of newly diagnosed membranous nephropathy (MN) is to evaluate for secondary forms of the disease, and cancer screening is particularly important in patients >65 years of age. Testing for phospholipase A2 receptor (PLA2R) antigen is used to help distinguish primary (PLA2R antigen-positive) from secondary (PLA2R antigen-negative) forms of membranous nephropathy.
A 46-year-old woman is evaluated for a serum creatinine level of 2.6 mg/dL (229.8 µmol/L). Her baseline serum creatinine level 3 months ago was 0.9 mg/dL (79.6 µmol/L). She has no symptoms. Two years ago, she started losartan and amlodipine for hypertension. One year ago, she started omeprazole for gastroesophageal reflux disease and naproxen for knee osteoarthritis. Eight months ago, she began atorvastatin for hyperlipidemia.
On physical examination, temperature is 37.0 °C (98.6 °F), and blood pressure is 138/86 mm Hg. The remainder of the examination is unremarkable.
Urinalysis shows the following: specific gravity 1.015; pH 5.5; 1+ erythrocytes; 3+ leukocytes; 1+ leukocyte esterase; no nitrates; and >100 leukocytes/hpf with leukocyte and granular casts.
Which of her medications should be discontinued?
Naproxen and omeprazole
Acute interstitial nephritis can be caused by NSAIDs and PPIs in the absence of fever, rash, or eosinophilia.
A 73-year-old woman is evaluated during a follow-up visit for stage G4 chronic kidney disease. She reports no uremic symptoms. Medical history is also significant for hypertension. Medications are atenolol, chlorthalidone, cholecalciferol, hydralazine, and nifedipine. Vitals/exam are normal.
Labs: Calcium 8.7 mg/dL, Creatinine 2.0 mg/dL, Phosphorus 5.4 mg/dL, Parathyroid hormone 97 pg/mL, 25-hydroxyvitamin D 60 ng/mL, eGFR 24.
What is the most appropriate management?
Low phosphate diet
In patients with CKD and hyperphosphatemia, the initial step in management is a low phosphate diet. The next step is addition of a phosphate binder.
A 56-year-old man is evaluated for weakness after completing a second cycle of chemotherapy for a soft-tissue sarcoma recently excised from the right thigh. Medications are ifosfamide, doxorubicin, and mesna. Vitals are normal. Generalized weakness is noted. There is a healing surgical scar on the upper right thigh. The remainder of the examination is normal.
Labs: Creatinine 1.6 mg/dL, Sodium 136 mEq/L, Potassium 3.5 mEq/L, Chloride 106 mEq/L, Bicarbonate 18 mEq/L, Glucose 88 mg/dL, Phosphorus 1.2 mg/dL, Fractional excretion of phosphorus 10%, Urinalysis: pH 7.0, no blood, 3+ protein, 2+ glucose, no leukocyte esterase
What is the most likely cause of this patient's hypophosphatemia?
Proximal renal tubular dysfunction
In patients with hypophosphatemia, proximal renal tubular phosphate dysfunction can be identified by a fractional excretion of phosphorus >5%.
A 65-year-old man is evaluated for fatigue and weakness progressing over the last 3 months. His medical history is otherwise unremarkable, and he takes no medications. Physical and vitals are normal.
Labs: Hemoglobin 9 g/dL, Albumin 3.0 g/dL, Creatinine 0.9 mg/dL, Sodium 138 mEq/L, Potassium 3.4 mEq/L, Chloride 118 mEq/L, Bicarbonate 14 mEq/L, Glucose 74 mg/dL, Phosphorus 2.1 mg/dL, Total protein 8.0 g/dL; Urinalysis: pH 5.0, no blood, no protein, no erythrocytes, 1+ leukocytes, trace glucose.
What is the most likely cause of this patient's laboratory findings?
Type 2 (proximal) renal tubular acidosis
Characterized by a normal anion gap metabolic acidosis, hypokalemia, glycosuria (without hyperglycemia), low-molecular-weight proteinuria, and renal phosphate wasting.
An 81-year-old woman is evaluated for abrupt onset of lower extremity edema that began 2 weeks ago and has progressed to generalized edema. Medical history is significant for hypertension. Her only medication is amlodipine. Vitals are normal. There is periorbital edema, ascites, and pitting edema of the forearms and lower extremities to the thighs.
Labs: Albumin 1.6 g/dL, Total cholesterol 364 mg/dL, Creatinine 2.8 mg/dL (2 months ago: 0.7 mg/dL); Urinalysis no blood, 4+ protein.
Kidney ultrasound with Doppler shows normal-sized echogenic kidneys with no hydronephrosis; there are no abnormalities on Doppler flow.
What is the most likely diagnosis?
Minimal change glomerulopathy with acute kidney injury.
The classic presentation of minimal change glomerulopathy is sudden-onset nephrotic syndrome with abrupt appearance of edema and, eventually, anasarca. Up to 25% of adults with minimal change glomerulopathy may have AKI, with a particular risk in older patients with hypertension, low serum albumin levels, and heavy proteinuria.
A 66-year-old man is evaluated in the hospital for acute kidney injury following percutaneous coronary angiography and stent placement 48 hours ago. His medical history is also significant for hypertension, hyperlipidemia, type 2 diabetes mellitus, and diabetic kidney disease. Medications are lisinopril, hydrochlorothiazide, basal and prandial insulin, atorvastatin, metoprolol, clopidogrel, and aspirin. On physical examination, blood pressure is 132/88 mm Hg, and pulse rate is 58/min without postural changes. Skin is warm and dry. The remainder of the examination is normal.
Labs: Hematocrit 36%, Platelet count 127,000/uL, BUN 54 mg/dL, Creatinine 3.6 mg/dL, Urinalysis: specific gravity 1.010, pH 5.5, trace protein, trace leukocytes, 1-3 erythrocytes/hpf, 1-3 leukocytes/hpf, 3-5 granular casts/hpf.
Kidney ultrasound shows a 10.5-cm right kidney, 11.3-cm left kidney, and normal cortical echogenicity; there is no hydronephrosis.
What is the most likely diagnosis?
Contrast-associated acute tubular necrosis
Characterized by an increase in the serum creatinine 24 to 48 hours after contrast exposure.
A 60-year-old woman is evaluated during a follow-up visit for stage G3 proteinuric chronic kidney disease due to type 2 diabetes mellitus. Medications are lisinopril and metformin. On physical examination, blood pressure is 137/80 mm Hg, and pulse rate is 83/min; other vital signs are normal. The remainder of the examination is normal.
Labs: A1c 8.3%, Creatinine 1.3 mg/dL, Potassium 4.3 mEq/L, eGFR 45, Spot urine protein-creatinine ratio 3680 mg/g.
What is the most appropriate additional treatment?
Addition of an SGLT-2 inhibitor
SGLT-2 inhibitors slow the progression of chronic kidney disease and reduce the risk of death from kidney or cardiovascular complications in patients with diabetic kidney disease.
GLP-1 receptor agonists reduce the risks for cardiovascular events and hypoglycemia and appear to possibly slow chronic kidney disease progression.
A 45-year-old woman is evaluated for a 3-day history of lower extremity weakness. Medical history is significant for hypertension, T2DM, and GERD. Medications are lisinopril, metformin, canagliflozin, and pantoprazole. On exam, vitals are normal. Knee and ankle reflexes are decreased. Muscle strength is 4/5 in the lower extremities.
Labs: Creatinine 1.1 mg/dL, Sodium 138 mEq/L, Potassium 3.0 mEq/L, Chloride 104 mEq/L, Bicarbonate 23 mEq/L, Magnesium 1.1 mg/dL.
What is the most likely cause of this patient's hypokalemia?
Pantoprazole
PPIs are a cause of hypomagnesemia, which typically occurs after long-term use and is an important cause of hypokalemia.
A 25-year-old woman is evaluated for weakness and muscle cramps. During the past 3 months she has lost 33 pounds. She has no other medical problems and takes no medications. BP is 124/72, HR 100/min, RR 18/min. BMI is 36. Muscle strength is 4/5 in the upper and lower extremities. Neuro exam is otherwise normal.
Labs: Creatinine 0.9 mg/dL, Sodium 135 mEq/L, Potassium 2.4 mEq/L, Chloride 79 mEq/L, Bicarbonate 44 mEq/L, ABG: pH 7.61, PCO2 45 mmHg, Urine chloride 3 mEq/L.
What is the most likely diagnosis?
Surreptitious vomiting
Saline-responsive metabolic alkalosis presents with a low urine chloride of <15 mEq/L; the most common causes are vomiting, NG suction, and diuretic use.
A 43-year-old man is evaluated during a follow-up visit for a recent biopsy-confirmed diagnosis of IgA nephropathy. He is asymptomatic. He has no other medical problems and takes no medications. Vitals/physical are normal.
Labs: Albumin 4.0 g/dL, Creatinine 0.95 mg/dL, Urinalysis: 3+ blood, 2+ protein; 24-Hour urine protein excretion 725 mg/24 h
What is the most appropriate management?
First-line therapy for IgA nephropathy is either an ACE inhibitor or ARB. Treatment with high-dose glucocorticoids is associated with an increased risk for adverse events and may not improve kidney function.
A 54-year-old man is evaluated for the nephrotic syndrome 10 days after undergoing a kidney biopsy. He reports normal urine volume and no hematuria. He has noticed mild bilateral flank aches during the past 2 days. Prebiopsy serum creatinine level was 0.9 mg/dL (79.6 µmol/L). Medical history is also significant for hyperlipidemia. Medications are furosemide and atorvastatin. On physical examination, temperature is 37.0 °C (98.6 °F), blood pressure is 148/88 mm Hg, and pulse rate is 72/min. Bilateral costovertebral angle tenderness is noted. There is 2+ lower extremity edema. The remainder of the examination is normal. Laboratory studies show a serum creatinine level of 3.2 mg/dL (282.9 µmol/L). Urinalysis shows a specific gravity of 1.012; pH of 5.0; 3+ blood; 3+ protein; 1+ leukocytes; >100 erythrocytes/hpf; occasional leukocytes; and no casts. Kidney biopsy shows membranous nephropathy with minimal interstitial fibrosis and no glomerulosclerosis.
What is the most likely diagnosis?
Renal vein thrombosis.
Complication of the nephrotic syndrome and is most commonly associated with membranous nephropathy. Preferred imaging studies in patients with AKI or eGFR of <30 include renal ultrasonography with Doppler and renal venography.
A 43-year-old man is evaluated during a routine follow-up visit for end-stage kidney disease due to IgA nephropathy. He received a living-donor related kidney transplant 5 years ago. He is asymptomatic. Medical history is also significant for hypertension. Medications are prednisone, mycophenolate mofetil, tacrolimus, lisinopril, metoprolol, and atorvastatin. All physical examination findings, including vital signs, are normal. Laboratory studies show a serum creatinine level of 0.8 mg/dL (70.7 µmol/L) and a fasting blood glucose level of 99 mg/dL (5.5 mmol/L).
What is the most appropriate screening test at this time?
Skin examination
Kidney transplant recipients are at increased risk for multiple types of skin cancer and should undergo annual skin examination.