Renal & Electrolyte Disorders

Reference: Davidson 23rd; P-428

An arterial blood gas (ABG) is a test that measures the oxygen tension (PaO2), carbon dioxide tension (PaCO2), acidity (pH), oxyhemoglobin saturation (SaO2), and bicarbonate (HCO3) concentration in arterial blood. Some blood gas analyzers also measure the methemoglobin, carboxyhemoglobin, and hemoglobin levels.

Reference: Davidson 23rd; P-147

Reference: Davidson 23rd; P-430

ABM 477

Reference: Davidson 23rd, Fig. 21.7 (39 BCS Question)

Explanation: The most common cause of hypocalcaemia is a low serum albumin with normal ionised calcium concentration. For details, please see Davidson 23rd, Box-18.33

The kidneys have a rich blood supply and receive approximately 20%–25% of cardiac output through the renal arteries, which arise from the abdominal aorta. The renal arteries undergo various subdivisions within the kidney, eventually forming interlobular arteries that run through the renal cortex. These eventually give rise to afferent glomerular arterioles that supply the glomeruli.

Reference: Davidson 23rd; P-429

Saline/ Chloride responsive:  Associated with hypovolemia and  responds to N/S infusion

•Ingestion of Alkaline Drugs
•GIT Cause
•Diuretic administration

Reference: Davidson 23rd; P-419

Reference: Davidson 23rd; P-429

Reference: Davidson 23rd; P-429

Reference: Davidson 23rd; P-428

Reference: Davidson 23rd; P-358

Explanation: Microalbuminuria is the most sensitive test for detecting early diabetic nephropathy. Davidson explains that albumin excretion increases in the early stages of kidney damage, even before significant declines in GFR or rises in serum creatinine are seen. Harrison emphasises that early detection through microalbuminuria allows for timely interventions to slow disease progression.

Reference: Davidson 23rd; P-357

Dyspnea but chest is clear—pulmonary embolism, metabolic acidosis (diabeti ketoacidosis, renal failure, lactic acidosis salicylate poisoning), severe anemia, shock, pneumocystis jiroveci pneumonia, psychogenic.

Dyspnea with stridor (indicates upper airway obstruction)—foreign body or tumor, acute epiglottitis, anaphylactic reaction, laryngeal trauma, laryngeal fracture.

Reference: Davidson 23rd; P-351

Each kidney is approximately 10–13 cm in length in healthy adults;they are located retroperitoneally on either side of the aorta and inferior vena cava between the 12th thoracic and 3rd lumbar vertebrae (Fig. 18.1A). The right kidney is usually a few centimetres lower because the liver lies above it. Both kidneys rise and descend several centimetres with respiration.

Reference: Davidson 23rd; P-357

Reference: Davidson 23rd; P-601

Reference: Davidson 23rd; P-429

Reference: Davidson 23rd; P-434

GROSS  HEMATURIA
•Trauma
•Tumor
•IgA nephropathy
•Alport syndrome

Explanation: An elevated blood urea with normal creatinine concentration implies severe bleeding

Reference: Davidson 23rd; P-389

ABM 474

Reference: Davidson 23rd, Box-15.11

Hyperkalemia
Drug causes
β-blockers
·Angiotensin-converting enzyme (ACE) inhibitors
·Angiotensin-receptor blockers (ARBs)
·Spironolactone
·Eplerenone
·Calcineurin inhibitors: Cyclosporin, Tacrolimus

Reference: Davidson 23rd; P-365

2 equations
1.Hendersson  Hasslebach equation
2.Anion  Gap

Type I RTA is characterized by:

•Impaired hydrogen ion secretion in Distal  tubule
•Hypokalemia
•Hypocitraturia
•Hypercalciuria
•Nephrocalcinosis
•Renal Stones

Reference: Davidson 23rd; P-417

Type B: Impaired Lactic acid  metabolism
•Severe sepsis
•Hepatic & Renal failure
•Drugs- Metformin, Ethanol
•Diabetes mellitus
Type A: Increased production, due to:
Hypotension – Shock, Cardiac failure
Tissue hypoxia:
Mitochondrial  dysfunction (CO, Cyanide) Severe anemia

Explanation: Insulin causes hypokalaemia, option A,B,D Drugs causes hyperkalaemia

The major unmeasured cations are calcium,  magnesium, gamma globulins.

Reference: Davidson 23rd; P-363

Reference: Davidson 23rd; P-674

Clinical features

The typical presentation is for a reduced eGFR to be found incidentally during routine blood tests, often during screening of high-risk patients, such as those with diabetes or hypertension. Most patients with slowly progressive disease are asymptomatic until GFR falls below 30 mL/ min/1.73 m 2 and some can remain asymptomatic with much lower GFR values than this. An early symptom is nocturia, due to the loss of concentrating ability, but this is non-specific. When GFR falls below 15–20 mL/ min/1.73 m2 , symptoms and signs are common and can affect almost all body systems, but are often non-specific and may not immediately raise suspicion of kidney disease (Fig. 18.22). They typically include tiredness or breathlessness, which may, in part, be related to renal anaemia or fluid overload. With further deterioration in renal function, patients may suffer pruritus, anorexia, weight loss, nausea, vomiting and hiccups. In very advanced renal failure, respiration may be particularly deep (Kussmaul breathing) due to profound metabolic acidosis, and patients may develop muscular twitching, fits, drowsiness and coma.

Adrenal insufficiency & hypothyroidism may cause hyponatremia. Hypothyroidism decreases cardiac output and GFR and thus increased AVP secretion leading to hyponatremia.

Explanation: About 65% of the filtered sodium load is reabsorbed in the proximal renal tubule

Reference: Davidson 23rd; P-432

EXplanation: The nephritic syndrome is characterised by the presence of haematuria in association with hypertension, oliguria, fluid retention and reduced/declining renal function

Reference: In pre-renal AKI, usually develops hypotension not hypertension. Davidson 23rd, Box-15.25

Explanation: The presence of leucocytes and nitrites in urine is indicative of renal tract infection

Explanation: Main side effects of ACE inhibitors are: Renal impairment and Hyperkalemia

Reference: Davidson 23rd; P-393

Explanation: Oliguria is defined as being present when less than 400 mL of urine is passed per day, whereas anuria is deemed to exist when less than 100 mL of urine is passed per day

In polycystic kidney disease erythropoietin production isn’t hampered, even there is increased production.

Reference: Davidson 23rd, Box-15.10

Lindsay’s nails
White/brown ‘half-and-half’ nails
Found in-  Chronic kidney disease

Macleod 14/box 3.4

1.
Massive proteinuria, with the daily loss of 3.5 gm or more of protein (less in children)
2.
Hypoalbuminemia, with plasma albumin levels  less than 3 gm/dL
3.
Generalized edema
4.
Hyperlipidemia and lipiduria

Reference: Davidson 23rd; P-411