Nephrology notes Flashcards
What are the indications for emergency haemodialysis?
What are dialyzable drugs/toxins?
How can serotenergic syndrome affect the kidneys?
What should the management be?
- Due to increased muscle rigidity it can result in rhabdomyolysis (releases K (arrhythmia), myoglobin, creatine kinase, phosphate) which may further lead into compartment syndrome (compromising blood supply to limbs)
- Myoglobin has toxic effect on renal tubules (esp proximal renal tubules). Interacts with Tamm-Horsfall protein in the distal tubules and result in cast formation in the presence of acidic urine. This leads to urinary obstruction.
Mangement
* If myoglobinuria –> should IV fluid resuscitation
* Sodium bicarbonate to make the urine alkali and prevent formation of renal casts (reduce chance of urinary obstruction) further worsening renal function
What are the prognostic factors of PKD?
PKD1 has early presentation and more severe with median starting dialysis around 50 years old (PKD2 median dialysis starting age around 70 years old)
What is the most common presenting SS of PKD and why?
What CBC and urinanalysisresults will be present?
- Loin pain (enlarged kidney) will stretch the surrounding muscles
- Refractory hypertension
- Family history (autosomal dominant if presentation in adulthood, autosomal recessive in children)
CBC results
* Occult polycythemia: cysts become stretched and compress on blood suppplies supplying kidney inducing hypoxia causing a reflex increased EPO production.
* There will be less anemia than non PCK patients with same dgree of renal dilatation
Urinanalysis: no significant proteinuria in most cases (if present think underlying DM)
Uremic encephalopathy
- Pathophysiology
Bedside teaching - Max
Accumulation of amino acid metabolites alter neuronal metabolism, alter balance of excitatory and inhibitory effects, eventually causing neuronal cellular damage and cell death
Notable metabolites that are neurotoxic include Guanidine compounds (guanidinosuccinic acid and guanidine, methyguanidine), Kynurenine, 3-hydroxykynurenine
Neurotoxic effect is compounded by metabolic disturbances such as acidosis, electrolyte disturbances (i.e. HypoNa, HyperK, HypoCa, HyperMg), dehydration or over-hydration, leading to neuronal inflammation and increased brain microvascular leakage
Uremic encephalopathy
Clinical presentation
Clinical presentation:
- May be the first indication of metabolic disturbances
- Wide range of S/S: Loss of memory, impaired concentration, depression, delusions, lethargy, irritability, fatigue, insomnia, psychosis, stupor, catatonia, and coma
- Myoclonic jerks, asterixis, chorea; Dysarthria, seizure, tetany
Uremic encephalopathy
Ix and diagnosis
- BUN for urea level: over 40mg/dL (normal <8)
- CBC (NcNc anemia)
- Electrolyte profile (HypoNa, HyperK, HypoCa, HyperPO4)
- Arterial blood gas (Metabolic acidosis with high Anion gap)
- RFT
- urinalysis for proteinuria (+/- Autoimmune markers, SFLC assays…)
EEG:
- Acute uremia: EEG is characterized by irregular low voltage with slowing of the posterior dominant alpha rhythm and occasional theta bursts.
- Characteristic findings are prolonged bursts of bilateral, synchronous slow and sharp waves or spike and waves.
Uremic encephalopathy
Treatment
General: Low-sodium, low phosphate, low potassium diet, Low-protein diet, 30kcal/kg/day, bed rest, adequate hydration
Correction of electrolyte disturbances: HyperK, HypoCa with calcium gluconate or calcium carbonate, metabolic acidosis with sodium bicarbonate
Renal replacement therapy
Seizure: Anticonvulsants at lower-than-normal doses due to low albumin levels, Levels of anticonvulsant drugs must be closely monitored to prevent toxicity
Surgery: renal transplantation, neurosurgical care for subdural hematoma or ICH
Manage cardiovascular complications: ultra-filtration related arterial hypotension causing ischemic stroke; thromboembolic ischemic CVA, concomitant hypertensive encephalopathy…etc
Uremic pericarditis
Pathophysiology
Pathophysiology
Inflammation of visceral and parietal pericardium by accumulated metabolic toxins
Notable metabolites: urea, creatinine, methylguanidine, guanidinoacetate, parathyroid hormone, beta2-microglobulin, uric acid
Types: Uremic pericarditis, dialysis-associated pericarditis
Uremic pericarditis
Clinical presentation
Uremic pericarditis: slow onset anterior chest pain/ present with isolated pericardial friction rub
Potentially fatal progression into cardiac tamponade: tachycardic, hypotensive, and has distended neck veins
Uremic pericarditis
Ix and diagnosis
Blood test:
- BUN >40mg/dL
- CBC, inflammatory markers, renal and liver function tests: raised erythrocyte sedimentation rate and C-reactive protein
- creatine kinase troponins: may be elevated (not diagnostic)
Imaging:
- Electrocardiogram: diffuse ST and T-wave elevations (typically diffuse and not localized to coronary artery territory c.f. STEMI)
- Chest X-ray: increased cardiac silhouette,
- Echocardiogram: restrictive pattern due to the stiffness of the fibrous pericardium as a result of adhesions, systolic right atrial collapse, with equalization of pressure in all cardiac chambers and swinging septal position
Uremic pericarditis
Treatment
General: Low-sodium, low phosphate, low potassium, low-protein diet, 30kcal/kg/day, bed rest, adequate hydration
Correction of electrolyte disturbances HyperK, HypoCa with calcium gluconate or calcium carbonate, metabolic acidosis with sodium bicarbonate
Intensive dialysis (HD) for 5-7 days with heparin-free hemodialysis (reduce the risk of intrapericardial haemorrhage)
No fluid removal to avoid hypotension and cardiovascular collapse
Refractory to intensive dialysis: systemic or intrapericardial NSAIDs and corticosteroids (e.g. Triamcinolone hexacetonide (synthetic corticosteroid))
Refractory to all medical treatment for 7 days or hemodynamically unstable: pericardiocentesis or pericardiectomy
Dermatological manifestations of uremia
- Xerosis (abnormally dry skin or mucosa)
- Pruritis: starts at stage 4 CKD, 6 months after starting dialysis. Cutaneous manifestations of pruritus include excoriations, prurigo nodularis, and lichen simplex chronicus
Pigmentary alterations:
- brown–to–slate-gray discoloration: hemosiderin deposition in association with iron overload from excessive transfusions
- yellowish hue: retained urochromes and carotene deposited in the epidermis and subcutaneous tissues
- Hyperpigmentation: increase in melanin production due to increase in poorly dialyzable beta-melanocyte stimulating hormone
Half and half nails
Alopecia
Uremic frost (rare): due to concentration of urea in sweat and evapouration of sweat deposit crystals in skin
Bullous disease of dialysis: secondary to iron overload
Arterial steal syndrome: proximal shunting of blood causing hand ischemia
Uremic anemia
Causes
Deteriorating renal function – deficient erythropoietin
Medications and dietary restriction
Anemia of chronic illness
Uremic anemia
Treatment target
Indication of treatment
Options
Goal of treatment:
- mitigate symptoms
- reduce blood transfusion
- treat absolute or functional iron deficiency
- target Hb should be individualized: within 10 to 11.5 g/dL. Excessive Hb can lead to hyperviscosity syndrome and directly increase mortality
Indications:
- Hb <11 g/dL
- Symptomatic anemia
- CKD stage 4/5 with no other cause identified (eg blood loss, folic acid or vitamin B12 deficiency)
Treatment options:
- Iron repletion: oral iron, iv iron dextran, iv iron sucrose, iv iron carboxymaltose
- Oral iron for PD, IV iron for HD
- ESA (Erythropoiesis Stimulating Agents): SC or IV
- Hypoxia inducible factor proline hydroxylase inhibitor (HIF proline hydroxylase inhibitor)
- Blood transfusion (indicated by acute blood loss, hemolysis, severe sepsis)
CKD - BMD
Clinical presentation
- Fractures, bone and joint pain
- Skeletal deformities, growth retardation in children
- Deposition of calcium-phosphate complexes in vascular tissue (medial calcification-> hypertension, stroke, MI)
- Deposit in valvular tissue (valvular dysfunction, MI)
- Deposit in soft tissue (metastatic calcification, most commonly in periarticular regions)
- Calciphylaxis (ulcers, infection with sepsis)
CKD - BMD
Types of renal osteodystrophy
High bone turnover
- Secondary hyperPTH
- changes in material composition and nanomechanical properties (mineral-to-matrix ratio, carbonate-to-phosphate ratio, hardness, and shape-independent material stiffness)
Low bone turnover/adynamic bone disease
- More commonly in PD and HD patients
- Oversuppression of PTH with normal mineralization due to early usage of vit D analogs and Ca-containing PO4 binders
- changes in microstructural parameters (low cancellous bone volume, and trabecular thickness, absent osteoid accumulation)
CKD - BMD
Ix and diagnosis
RFT: GFR <60mL/min
Electrolytes and metabolites:
- serum calcium, phosphate, PTH, 25(OH)D (calcidiol) levels
- Bone-specific alkaline phosphatase for bone turnover
BMD testing: by dual energy X-ray absorptiometry to assess fracture risk
Gold standard for evaluation and diagnosis of renal osteodystrophy is bone biopsy. (NOT routinely done)
Lateral AXR for vascular calcification, echocardiogram for valvular calcification
CKD - BMD
Treatment
Based on serial assessments of phosphate, calcium, and PTH levels
Dietary restriction (<900mg/d): avoid excessive milk, cheese, eggs, protein-rich food (esp processed)
Phosphate binders: sevelamer, lanthanum (non-Ca), CaCO3, Ca acetate (Ca-based)
Treatment of ↓Ca, ↓vitamin D, ↑PTH: should be done AFTER correction of ↑PO4:
- Calcitriol/synthetic analogue: active form of vitamin D, usually first choice (might correct Ca but exacerbate PO4 level due to concomitant increase absorption of both in gut)
- Calcimimetics (cinacalcet, etelcalcetide): ↑sensitivity of parathyroid calcium-sensing receptor to calcium → ↓PTH secretion
- Parathyroidectomy
Treatment of bone disease:
- Bisphosphonate, denosumab and other Tx of osteoporosis
- guided by BMD, fragility fractures ± bone biopsy
What are the 2 associated viruses with renal transplantation?
- BK virus
- CMV