AKI Case – Aches and pains

You are the junior doctor working in the acute medical unit. A 78 year old lady is referred to the department following investigation for general malaise, arthralgia and myalgia.

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You take a history from the patient

She has been generally tired and unwell for around 6 weeks. She has no other specific symptoms but she has noted that her urine has become darker over the last few days. She is still passing good volumes of urine. Her shoes have been a little tighter than normal over the last few days and she has been struggling with her mobility.

She has a past medical history of rheumatoid arthritis and peptic ulcer disease. Both of these have been stable over the past year. She uses occasional antacids and methotrexate and folic acid. No OTC medications

A=Maintaining own

B= Chest clear, good AE throughout

C= WWP, JVP 4cms, Mild pedal oedema, HS1+2+0, BP 168/95,

D = visible swelling and deformity of her hands with boutonnier and swan necking of fingers, no obvious heat or signs of active inflammation, Abdo soft non-tender, no palpable organomegally, no flank tenderness

What investigations would you like to perform?

Yes part of standard investigations results = Creat 320 (80 last year), urea 16.0, K 5.6, Na 137, calcium and phosphates normal

Again important in an individual with fatigue and rheumatoid arthritis as some medications used to treat it can lead to abnormalities in full blood count. Results – Hb 125g/dl, WCC 7.4, Plt 350

Whilst hypothyroidism can cause malaise, you would expect her to have other symptoms of this. This was not done in this patient

In a patient with symptoms of peripheral oedema, and abnormal U+Es this would guide in determining if there is proteinuria or haematuria. Patients results Protein +++, blood +++, all other negative

Whilst rhabdomyolysis can cause myalgia and arthralgia there is usually a predisposing event eg fall, excessive exercise, immobility

You realise that you need to get advice. Who would you contact and what would you tell them is the issue?

You might ask the renal team and tell them she is presenting with acute kidney injury. Identified by normal haemaglobin, calcium and phosphate

Where do you think the issue is?

This lady is hypertensive and oedematous – this points to another cause

Yes a primary renal pathology is indicated in this lady’s presentation

This lady is passing good volumes of urine with no indication of obstructive symptoms. It is important to carry out a renal ultrasound to rule this out.

She undergoes renal ultrasound scanning which returns with no structural abnormalities in the renal tract.

Which of the following do you think is causing her renal impairment?

Blood pressure is not low leading to this. Whilst methotrexate is a very rare cause of ATN, there is another more likely diagnosis.

This is unlikely, as these are usually associated with falling Hb and low platelet count, and microangiopathic haemolytic anaemia. She has none of these

As the name suggests allergy is the commonest cause of this and less haematuria and proteinuria than this, she gives no history of prolonged severe or resistant hypertension. No signs of large vessel disease elsewhere.

This is the most likely diagnosis causing both blood and protein in his urine, and he has lost function. In fact the timescale suggests ‘Rapidly Progressive’ glomerulonephritis, RPGN. A biopsy of often shows crescents. There is also evidence of PPI and methotrexate can also be causes of this

Usually associated with back pain, high fever, but not always. Unlikely to be going on for 6 weeks

There are many other renal causes of acute kidney injury, click reveal to see them

  • Renal Artery Stenosis – There are no specific signs. Hypertension is usual. Urinary dipstick testing is normal or mildly abnormal. Hypokalaemia may occur because of secondary hyperaldosteronism.  AKI tends to be in the context of ACE-inhibition
  • Haemolytic Uraemic Syndrome or Thrombotic Thrombocytopenic Purpura – Haemolytic anaemia, low platelets and renal failure
  • Glomerulonephritis – the Nephritic ones in particular can present acutely
  • Acute Tubular Necrosis -can be associated with ischaemia or toxicity (usually drug-related or exogenous toxin) contrast and gentamycin the two main culprits, but can get endogenous toxic ATN due to myoglobin release – rhabdomyolysis – or high levels of urate or phosphate – tumour lysis syndrome
  • Acute Interstitial Nephritis – refers to an allergy type reaction characterised by interstitial infiltration by lymphocytes (again usually drug-related – penicillin and Proton-pump inhibitors especially).

Now that you have the most likely diagnosis, what further investigations would you like to complete? Write them down and click reveal following this.

Any disease at the nephritic end of the spectrum of glomerulonephritis can be aggressive enough to trigger crescent formation and Rapidly Progressive Glomerulonephritis (RPGN). But the ones that do this most severely and most frequently are:

  • Small vessel vasculitis
  • Anti-GBM disease
  • Lupus nephritis

Immunology tests can help differentiate between some of these conditions. The screen should include  Anti-GBM antibody (anti-GBM disease) ANCA (anti-neutrophil cytoplasmic antibody) (Small vessel vasculitis, but false positives and negatives can occur) Complement (CH50, C3 and C4) (SLE, subacute bacterial infection and post-infectious glomerulonephritis are three important explanations in the acute setting.  Complement deficiencies also predispose to some glomerulonephritis) (MCGN),  ANA (Anti-nuclear antibody) ( SLE, but non-specific esp at low titre, and may be positive in a range of ‘connective tissue disorders’) Anti-double stranded-DNA (if ANA positive) (SLE- more specific.

Though any disease that causes GBM breaks can, the other nephritic-type diseases that do as this most often are IgA nephropathy/Henoch – Schonlein purpura, post-infection glomerulonephritis.

The renal team see the patient and take over his care. You enquire after the patient a few days later and hear that he has undergone a renal biopsy. This shows a crescentic glomerulonephritis, but immunofluoresence on the biopsy was negative.

Which Serological Test do you think will be positive? (mainly for interest)

Anti-GBM disease shows a crescentic glomerulonephritis, the Immunofluorescence pattern is a ribbon pattern.

Although the renal biopsy in Immune-complex deposition disease will show a crescentic glomerulonephritis, the immunofluorescence appearance is a granular or Starry-sky pattern.

Although the renal biopsy in Immune-complex deposition disease will show a crescentic glomerulonephritis, the immunofluorescence appearance is a granular or Starry-sky pattern.

Although the renal biopsy in Immune-complex deposition disease will show a crescentic glomerulonephritis, the immunofluorescence appearance is a granular or Starry-sky pattern.

Vasculitis is also referred to as Pauci-immune glomerulonephritis, referring to the lack of immunofluorescence on renal biopsy specimens.

She is treated for her vasculitis and remains under the vasculitis team for ongoing follow-up.