Buku Medicine


Show more


Show more

Parathyroid hormone

Quick tip: elevation in PTH in patients with CKD is a chronic problem from which the patient will come to no harm in the short term - management can be led by the renal team as an outpatient 

PTH levels increase as CKD progresses, initially as an adaptive mechanism to increase phosphate loss in the urine, to compensate for decreased phosphate filtration.  However, as PTH levels rise, so does the risk of CKD mineral bone disease (CKD-MBD). 

Key facts regarding CKD-MBD: 

  • Strongly associated with cardiovascular disease and mortality 
  • Target level for PTH is between 2-9 times the upper limit of normal 

Treatment is usually started in CKD stages 4 or 5, and is aimed at decreasing phosphate and PTH levels while keeping calcium within the normal range.  This is achieved by: 

  • advising low phosphate dietary intake, with help from renal dietitian colleagues 
  • phosphate binders, to decrease GI absorption 
  • replacing inactive vitamin D orally (it is unclear whether this is beneficial, though it is often done and is not considered detrimental) 
  • activated vitamin D products (reserved for severe and progressive hyperparathyroidism and dialysis dependant CKD) 
  • calcimimetics such as cinacalcet lower PTH and serum calcium in tertiary hyperparathyroidism  

See the app ‘Managing CKD Mineral Bone Disorder’ for more detail and for management algorithms for different biochemical parameters. 

Bicarbonate level

In the outpatient setting, patients with CKD may be prescribed oral sodium bicarbonate to counteract the associated metabolic acidosis.  It is common practice to consider replacement when levels around <20mmol/L, and then to target the normal range.  Patient are advised to decrease dietary acid load (eg. from animal protein) and to increase dietary base intake (eg. increase fruit and vegetable intake), though given dietary limitations on potassium intake this can be difficult. 

Serum bicarbonate levels of <22mmol/L are associated with: 

  • Increased risk of CKD progression 
  • Bone demineralisation 
  • Protein catabolism 
  • Hyperkalaemia 

Sodium bicarbonate therapy: 

  • Starting oral dose of 500mg three times daily reasonable, with uptitration to 1g TDS if required and tolerated 
  • Helps control hyperkalaemia 
  • Side-effects include GI upset and increased pill burden 
  • Unlike sodium chloride, it is not associated with hypertension, though levels above 26mmol/L are associated with increased heart failure and vascular calcification 
  • If made NBM on admission to hospital is a non-urgent medication which can be safely omitted 

"Renal screen" explained

Show more

Renal ultrasound findings

Quick tip: usual findings in long-standing CKD are small kidneys on ultrasound with a thin cortex, increased echogenicity and loss of corticomedullary differentiation 

Quick tip: In the setting of abnormal kidney function, an USS is helpful to  

  1. Exclude hydronephrosis 
  2. Measure kidney size 
  3. Confirm two kidneys present 
  4. Occasionally give the diagnosis e.g polycystic kidneys

Increased kidney size bilaterally, with normal kidney function and echogenicity 

  • Obesity 
  • Tall stature 
  • Steroid use 
  • Acromegaly 
  • Diabetes 
  • Leukaemia infiltrating kidneys (very rare) 

Asymptomatic, unilateral increase in kidney size 

  • Hypertrophy of one kidney due to decreased function of the other (eg. unilateral renal artery stenosis) 
  • Leukaemia (though usually affects both kidneys) 

Symptomatic, unilateral increase in kidney size 

  • Unilateral obstruction 
  • Pyelonephritis 
  • Acute vascular insult eg. renal vein thrombosis 


Varying echogenicity is not a reliable way to distinguish different causes of AKI, but in conjunction with the clinical picture may make certain conditions more or less likely. 

Normal or increased echogenicity with reduced kidney function 

  • Glomerulonephritis 
  • Acute interstitial nephritis 
  • Amyloid 
  • Multiple myeloma 
  • HIV nephropathy 
  • Pre-eclampsia 

Decreased cortical echogenicity 

  • Acute cortical necrosis 
  • Oedema 

Increased medullary echogenicity (normal cortex) 

  • Nephrocalcinosis 
  • Urate nephropathy 
  • Sickle cell disease 
  • Sjogren's syndrome 
  • Medullary sponge kidney 

Transplant meds levels

Quick tip: patients will usually take twice daily immunosuppressants at 10am and 10pm - this leaves time in the morning for trough levels to be taken before the dose.  

Quick tip: it can take several days in some centres to get tacrolimus and ciclosporin results, so the patient should continue taking their usual dose while results are awaited 

Renal transplant medications with commonly measured levels include tacrolimus, ciclosporin and sirolimus.   

All levels must be taken as trough levels, before the morning dose.  

Target ranges will be patient specific, factoring in: 

  • rejection risk 
  • infection and cancer risk 
  • other immunosuppression taken 
  • time since transplant 
  • current clinical situation 

As a rough rule of thumb, if used within a combination of immunosuppression and over one year since transplant, reasonable targets levels are: 

  • Tacrolimus 3-7ng/L 
  • Ciclosporin 100-150ng/L 
  • Sirolimus 4-7ng/L 

However, clearly, one should always discuss target levels and clinical situation of specific patients with the transplant team who knows the patient. 

There is no widely available laboratory test to measure mycophenolate levels.   





‘Managing CKD Mineral Bone Disorder’ - recommended app